CN111062482A - Quantum state reconstruction method, device and system and storage medium - Google Patents
Quantum state reconstruction method, device and system and storage medium Download PDFInfo
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Abstract
The invention discloses a quantum state reconstruction method, a device, a system and a storage medium, wherein the method is applied to quantum computing equipment and comprises the following steps: when a current pulse sequence sent by classical computing equipment is received, applying the current pulse sequence to a quantum state to be tested in a quantum system to obtain quantum experimental data corresponding to the current quantum state; determining the quantum state similarity between the current quantum state and the preset quantum state according to the quantum experimental data, and sending the quantum state similarity to the classical computing equipment, so that the classical computing equipment reconstructs the quantum state to be detected according to the quantum state similarity, or sends a gradient information acquisition request; when a gradient information acquisition request is received, gradient information corresponding to the quantum state similarity is determined according to the current pulse sequence, and the gradient information is sent to the classical calculation equipment, so that the classical calculation equipment updates the current pulse sequence according to the gradient information, and the quantum state reconstruction efficiency can be effectively improved.
Description
Technical Field
The embodiment of the invention relates to a quantum computing technology, in particular to a quantum state reconstruction method, a device, a system and a storage medium.
Background
Quantum computing is a new application field of quantum physics. With the rapid development of quantum computing technology, quantum computing can be performed in various quantum experimental platforms, such as nuclear magnetic resonance systems, superconducting quantum wires, diamond NV (Nitrogen-Vacancy) color centers, ion trap quantum computing, and the like.
After performing quantum calculations it is often necessary to read the state in which the quantum system is, i.e. to reconstruct the quantum state. At present, experimental data after multiple quantum experiments are usually processed to determine each unknown element in a quantum state one by one, so as to reconstruct the quantum state. However, as the number of qubits in a quantum system increases, the number of quantum experiments that need to be performed increases exponentially, so that the reconstruction complexity of the quantum state also increases exponentially, resulting in a significant reduction in reconstruction efficiency.
Disclosure of Invention
The embodiment of the invention provides a quantum state reconstruction method, a device, a system and a storage medium, which are used for effectively improving the reconstruction efficiency of quantum states.
In a first aspect, an embodiment of the present invention provides a quantum state reconstruction method, applied to a quantum computing device, including:
when a current pulse sequence sent by classical computing equipment is received, applying the current pulse sequence to a quantum state to be tested in a quantum system to obtain quantum experimental data corresponding to the current quantum state;
determining the quantum state similarity between the current quantum state and a preset quantum state according to the quantum experimental data, and sending the quantum state similarity to the classical computing equipment so that the classical computing equipment reconstructs the quantum state to be tested according to the quantum state similarity or sends a gradient information acquisition request;
when the gradient information acquisition request is received, determining the gradient information corresponding to the quantum state similarity according to the current pulse sequence, and sending the gradient information to the classical computing equipment, so that the classical computing equipment updates the current pulse sequence according to the gradient information.
In a second aspect, an embodiment of the present invention further provides a quantum state reconstruction method, applied to a classical computing device, including:
when a reconstruction starting instruction is detected, sending the initial pulse sequence serving as a current pulse sequence to quantum computing equipment;
when the quantum state similarity sent by the quantum computing equipment is received and the quantum state similarity is detected to be greater than or equal to the preset similarity, reconstructing the quantum state to be detected in the quantum system according to the current pulse sequence and the preset quantum state;
and when detecting that the quantum state similarity is smaller than the preset similarity, sending a gradient information acquisition request to the quantum computing equipment, updating the current pulse sequence according to the received gradient information, and sending the updated current pulse sequence to the quantum computing equipment.
In a third aspect, an embodiment of the present invention further provides a quantum state reconstruction apparatus, integrated in a quantum computing device, including:
the current pulse sequence applying module is used for applying the current pulse sequence to a quantum state to be tested in the quantum system when receiving the current pulse sequence sent by the classical computing equipment, and acquiring quantum experimental data corresponding to the current quantum state;
the quantum state similarity determining module is used for determining the quantum state similarity between the current quantum state and a preset quantum state according to the quantum experimental data and sending the quantum state similarity to the classical computing equipment so that the classical computing equipment reconstructs the quantum state to be tested according to the quantum state similarity or sends a gradient information obtaining request;
and the gradient information determining module is used for determining the gradient information corresponding to the quantum state similarity according to the current pulse sequence when the gradient information acquiring request is received, and sending the gradient information to the classical computing equipment so that the classical computing equipment updates the current pulse sequence according to the gradient information.
In a fourth aspect, an embodiment of the present invention further provides a quantum state reconstruction apparatus, integrated in a classical computing device, including:
the initial pulse sequence sending module is used for sending the initial pulse sequence serving as a current pulse sequence to the quantum computing equipment when a reconstruction starting instruction is detected;
the quantum state reconstruction module is used for reconstructing a quantum state to be detected in a quantum system according to a current pulse sequence and a preset quantum state when the quantum state similarity sent by the quantum computing equipment is received and the quantum state similarity is detected to be greater than or equal to the preset similarity;
and the current pulse sequence updating module is used for sending a gradient information acquisition request to the quantum computing equipment when detecting that the quantum state similarity is smaller than the preset similarity, updating the current pulse sequence according to the received gradient information, and sending the updated current pulse sequence to the quantum computing equipment.
In a fifth aspect, an embodiment of the present invention further provides a quantum state reconstruction system, where the system includes a quantum computing device and a classical computing device; wherein the content of the first and second substances,
the quantum computing device is for implementing the quantum state reconstruction method as provided in the first aspect;
the classical computing device is for implementing the quantum state reconstruction method as provided by the second aspect.
In a sixth aspect, the embodiments of the present invention further provide a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the quantum state reconstruction method provided in any embodiment of the present invention.
The embodiment of the invention carries out the quantum state reconstruction by mixing the quantum computing equipment and the classical computing equipment, and in the quantum state reconstruction process, the step that the reconstruction complexity increases exponentially along with the increase of the number of quantum bits is executed by the quantum computing equipment, and the step that the reconstruction complexity does not increase exponentially along with the increase of the number of quantum bits is executed by the classical computing equipment, so that the reconstruction complexity can be reduced by using the quantum computing mode. Specifically, the quantum computing device determines the quantum state similarity between the current quantum state and the preset quantum state by applying the current pulse sequence in the quantum state to be tested in the quantum system, and sends the quantum state similarity to the classical computing device, the classical computing device determines whether the current pulse sequence drives the quantum state to be tested to the preset quantum state according to the quantum state similarity, if so, reconstructs the quantum state to be tested according to the current pulse sequence, otherwise, a gradient information acquisition request needs to be sent, so that the quantum computing device determines the gradient information corresponding to the quantum state similarity and sends the gradient information to the classical computing device, the classical computing device can update the current pulse sequence according to the gradient information and send the updated current pulse sequence to the quantum computing device, so that the quantum computing device reapplies the updated current pulse sequence, and sequentially circulating until the quantum state to be detected is driven to the preset quantum state and the quantum state to be detected is reconstructed, so that the reconstruction complexity of the quantum state can be prevented from increasing exponentially, and the reconstruction efficiency of the quantum state is effectively improved.
Drawings
Fig. 1 is a flowchart of a quantum state reconstruction method according to an embodiment of the present invention;
fig. 2 is a flowchart of a quantum state reconstruction method according to a second embodiment of the present invention;
fig. 3 is a schematic structural diagram of a quantum state reconstruction device according to a third embodiment of the present invention;
fig. 4 is a schematic structural diagram of a quantum state reconstruction device according to a fourth embodiment of the present invention;
fig. 5 is a schematic structural diagram of a quantum state reconstruction system according to a fifth embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Example one
Fig. 1 is a flowchart of a quantum state reconstruction method according to an embodiment of the present invention, which is applicable to a case of determining an unknown quantum state in a quantum system. The method may be performed by a quantum state reconstruction apparatus integrated in a quantum computing device, which may be implemented by way of software and/or hardware. As shown in fig. 1, the method specifically includes the following steps:
s110, when a current pulse sequence sent by classical computing equipment is received, the current pulse sequence is applied to a quantum state to be tested in a quantum system, and quantum experimental data corresponding to the current quantum state are obtained.
The basic information unit in the classical computing device is a physical system with two states, represented by 0 and 1, the basic information unit in the quantum computing device is a qubit, the classical bit states 0 and 1 are replaced by two quantum states 0> and 1, wherein 0 can be represented by quantum state |0> with a spin orientation opposite to the direction of the external magnetic field, 1 can be represented by quantum state |1> with a spin orientation the same as the direction of the external magnetic field, i.e., the quantum information of one qubit can be represented by two quantum states with different orientations, and the quantum states can have properties, such as the quantum system can be in a linear superposition state of α |0> + β |1> carrying 0 and 1 simultaneously, thereby improving the computing performance of the device compared to the classical superposition state of 0 and 1.
A pulse sequence may refer to a sequence of multiple control pulses, wherein a control pulse may be, but is not limited to, a radio frequency pulse for controlling the state of a qubit to perform a corresponding rotation, etc. The control pulse can be designed based on quantum logic gates to realize corresponding control operations such as rotation. The current pulse sequence may refer to a pulse sequence used at the current time to control individual qubits in a quantum system, which was transmitted by a classical computing device. A quantum system may refer to a system under any physical system. For example, the quantum system may be, but is not limited to, a magnetic resonance system, superconducting quantum wires, diamond NV colour centers, ion trap quantum computing, and the like. Quantum experiments may refer to quantum computational experiments performed on quantum systems. The quantum state to be measured can be a quantum state subjected to dynamic evolution in a quantum system or a completely unknown quantum state to be measured. The current quantum state may refer to a system state in which a current pulse sequence is applied to a quantum state to be measured in the quantum system.
In particular, the quantum computing device may detect in real-time whether a current pulse sequence sent by a classical computing device is received. When the quantum computing device receives a current pulse sequence sent by a classical computing device, the current pulse sequence is applied to a quantum state to be tested in a quantum system for quantum experiment, so that the state of each quantum bit in the quantum state to be selected is correspondingly rotated, the state of the quantum system at the moment is regarded as the current quantum state, and an experiment measurement result obtained after the quantum experiment can be used as quantum experiment data corresponding to the current quantum state.
S120, determining the quantum state similarity between the current quantum state and the preset quantum state according to the quantum experimental data, and sending the quantum state similarity to the classical computing equipment, so that the classical computing equipment reconstructs the quantum state to be tested according to the quantum state similarity, or sends a gradient information acquisition request.
The preset quantum state may be a quantum state to which a quantum state to be detected needs to be driven. For example, the predetermined quantum state can be, but is not limited to, a quantum-base state, such as |0> <0| and |1> <1|, etc., wherein the quantum-base state |0> <0| can be a diagonal matrix mathematically, and only the first element on the main diagonal is 1 and the other elements are 0. Quantum experimental data may include, but is not limited to, the projected probability of a current quantum state in a particular direction of a preset quantum state. The quantum state similarity can be used for reflecting the fidelity between the current quantum state and the preset quantum state, and when the quantum state similarity is higher, the fidelity is also higher. The closer the quantum state similarity is to 1, the more similar the current quantum state is to the preset quantum state. Reconstructing the quantum state to be measured refers to determining the quantum state to be measured in the quantum system. The gradient information acquisition request may refer to a message for requesting acquisition of gradient information.
Specifically, the quantum state similarity between the current quantum state and the preset quantum state can be directly obtained in the quantum computing device according to quantum experimental data. For example, when the preset quantum state is the quantum-base state, the "determining the quantum state similarity between the current quantum state and the preset quantum state according to the quantum experimental data" in S120 may include: the method comprises the steps of obtaining the projection probability of the current quantum state in quantum experiment data on the quantum base state, and determining the projection probability as the quantum state similarity between the current quantum state and the quantum base failure state, so that quantum computing equipment can directly observe and obtain the quantum state similarity between the current quantum state and the quantum base failure state in a quantum experiment.
Illustratively, mathematically, the quantum state similarity between the current quantum state and the preset quantum state may be expressed as:
wherein, C refers to the current pulse sequence;
an inverse of the current pulse sequence; rhoaRefers to a predetermined quantum state; rho0Is the quantum state to be measured;
is in the quantum state rho to be measured0The current quantum state after the current pulse sequence C is applied; f (C) means the current quantum state
And a predetermined quantum state rhoaThe quantum state similarity between them; tr denotes a main diagonal summation function. It can be seen that the quantum state similarity can be a function associated with the current pulse sequence, and the specific value can be determined by the current pulse sequence, so that the current pulse sequence can be adjustedThe quantum state similarity is adjusted in a mode.
The quantum computing device can send the quantum state similarity to the classical computing device after determining the quantum state similarity between the previous quantum state and the preset quantum state based on the current pulse sequence, so that the classical computing device can judge whether the current pulse sequence drives the quantum state to be tested to the preset quantum state according to the quantum state similarity, and if so, can drive the quantum state to be tested to the preset quantum state according to the current pulse sequence C and the preset quantum state rhoaAnd (3) reconstructing the quantum state to be detected, namely reconstructing the reconstructed quantum state to be detected as follows:
if not, the current pulse sequence is indicated to be not in accordance with the requirements, the current pulse sequence needs to be updated, and at this time, the classical computing device can send a gradient information acquisition request to the quantum computing device, so that the quantum computing device determines the gradient information corresponding to the quantum state similarity.
And S130, when a gradient information acquisition request is received, determining gradient information corresponding to the quantum state similarity according to the current pulse sequence, and sending the gradient information to classical computing equipment so that the classical computing equipment updates the current pulse sequence according to the gradient information.
The gradient information can be used for reflecting the variable quantity of the quantum state similarity of the current pulse sequence, so that the current pulse sequence can be reasonably and accurately updated based on the gradient information, the current pulse sequence capable of driving the quantum state to be tested to the preset quantum state can be obtained as soon as possible, and the reconstruction efficiency is further improved.
Specifically, when receiving a gradient information acquisition request sent by a classical computing device, a quantum computing device may determine gradient information corresponding to the quantum state similarity according to a current pulse sequence in a finite difference manner, and send the gradient information to the classical computing device, so that the classical computing device may accurately update the current pulse sequence according to the gradient information, and send the updated current pulse sequence to the quantum computing device again, and the quantum computing device may re-execute the operations of steps S110 to S120 based on the updated current pulse sequence until the classical computing device can reconstruct a quantum state to be measured. Therefore, the quantum computing device is used for executing the determination operation of the quantum state similarity and the gradient information, the classical computing device is used for updating the current pulse sequence and reconstructing the quantum state to be detected according to the gradient information, and therefore the quantum state to be detected can be determined more quickly by utilizing a mixed working mode and a quantum state-based driving mode, and the reconstruction efficiency is improved.
For example, the current pulse sequence in this embodiment may refer to a parameterized pulse sequence, so that gradient information can be determined more conveniently. For example, the current pulse sequence includes a first preset number of sliced pulse sequences, where the first preset number is predetermined according to the number of quantum bits in the quantum system; the slicing pulse sequence is obtained by dividing parameters of the current pulse sequence, and the rotation direction of each bit in the slicing pulse sequence includes an x direction and a y direction.
Specifically, the present embodiment may determine, based on the correspondence in advance, a first preset number to be divided according to the number of quantum bits in the quantum system. When the number of the quantum bits is larger, the corresponding first preset number is also larger. For the reconstruction of most quantum states, the first preset number increases in a polynomial manner instead of an exponential manner with the increase of the number of quantum bits, so that the reconstruction complexity can be obviously reduced by using the hybrid reconstruction method provided by the embodiment. In this embodiment, all parameters in the current pulse sequence may be divided to obtain the slice parameters of the first preset number. Each slicing parameter corresponds to an x-direction and a y-direction. Each slicing parameter corresponds to a slicing pulse sequence. The execution time corresponding to each sliced pulse sequence may be determined based on the total application time of the current pulse sequence and a first preset number. For example, a division result obtained by dividing the total application time of the current pulse sequence by the first preset number may be determined as the execution time corresponding to each sliced pulse sequence. It should be noted that, in this embodiment, by performing fragmentation processing on the current pulse sequence, each fragment corresponds to an optimized degree of freedom, so that it is ensured that the current pulse sequence that drives the quantum state to be detected to the preset quantum state can be obtained.
Illustratively, when the current pulse sequence is a parameterized pulse sequence c (b), the parameter b in the current pulse sequence c (b) is divided into a first preset number of slice parameters, each slice parameter corresponds to an x-direction and a y-direction, that is, the parameter b can be mathematically expressed as:
b＝{bx[1],bx[2],...bx[M],by[1],by[2],...by[M]}
wherein M is a first predetermined number. The parameter b may be composed of M slicing parameters b in the x directionxAnd M slicing parameters b in the y directionyAnd (4) forming.
Based on this, the slicing pulse sequence C corresponding to the mth slicing parametermMathematically it can be expressed as:
where i is the imaginary part of the complex number; tau is the corresponding execution time of the slicing pulse sequence; h (H)0Is an intrinsic hamiltonian; bx[m]Is the mth slicing parameter in the x direction; by[m]Is the mth slicing parameter in the y-direction;
is a Pauli matrix applied to the kth qubit to rotate it in the x-direction;
is a Pauli matrix applied to the kth qubit to rotate it in the y-direction. n is the number of qubits in the quantum system.
Accordingly, the quantum state similarity between the current quantum state and the preset quantum state can also be expressed as:
wherein the content of the first and second substances,CMrefers to the Mth burst pulse sequence;
refers to the inverse sequence of the mth sliced pulse sequence.
Exemplarily, the "determining the gradient information corresponding to the quantum state similarity according to the current pulse sequence" in S130 may include: according to a preset gradient step length, adjusting each slicing parameter in the current pulse sequence one by one to obtain a second preset number of target pulse sequences, wherein the second preset number is twice of the first preset number; applying each target pulse sequence to a quantum state to be detected in a quantum system one by one to obtain target experimental data, and determining target similarity corresponding to each target pulse sequence according to the target experimental data; and determining the gradient information corresponding to each fragment parameter in the current pulse sequence according to the quantum state similarity, the target similarities and the preset gradient step length.
The gradient information corresponding to the quantum state similarity may include gradient information corresponding to each slice parameter in the current pulse sequence, so as to reasonably update each slice parameter in the current pulse sequence.
Specifically, in this embodiment, each slice parameter in the current pulse sequence may be increased by one preset gradient step one by one, and the current pulse sequence obtained by increasing one preset gradient step is determined as one target pulse sequence. Because the current pulse sequence contains the first preset number of the sliced pulse sequences, and each sliced pulse sequence corresponds to two directions of x and y, the target pulse sequence with the second preset number (namely 2 times of the first preset number) can be obtained. For example, the m-th slicing parameter b in the x-directionx[m]Is adjusted to bx[m]+ Δ, so that a target pulse sequence can be obtained.
Each target pulse sequence is applied to the quantum state to be measured in the quantum system one by one, and the target similarity corresponding to the target pulse sequence can be determined according to the obtained target experimental data, for example, the current quantum state obtained after the target pulse sequence is applied to the quantum state to be measured can be predictedAnd determining the projection probability on the quantum state as the target similarity between the current quantum state and the preset quantum state, namely the target similarity corresponding to the target pulse sequence. For each target pulse sequence, the gradient information corresponding to the adjusted slice parameter in the target pulse sequence may be determined according to the target similarity corresponding to the target pulse sequence, the quantum state similarity corresponding to the current pulse sequence, and the preset gradient step length. Illustratively, the current pulse sequence is C (b: b)x[m]) And determining the quantum state similarity corresponding to the current pulse sequence as follows: f (C (b: b)x[m]) If it is the m-th slicing parameter b) in the x-directionx[m]Is adjusted to bx[m]+ Delta, the target pulse sequence obtained is C (b: b)x[m]+ Δ), the determined target pulse sequence corresponding target similarity is: f (C (b: b)x[m]+ Δ)), then the m-th slice parameter b in the x-direction is approximated by the first orderx[m]Corresponding gradient information g (b)x[m]) Can be determined by the following formula:
it should be noted that, if the first preset number is M, in a loop iteration process, the number of quantum experiments required by the quantum computing device is as follows: 2M +1, wherein the 2M quantum experiments are used for determining gradient information corresponding to each fragment parameter in the current pulse sequence; the remaining 1 quantum experiment is used to determine the quantum state similarity between the current quantum state and the preset quantum state. When K times of loop iteration are needed to realize the reconstruction of the quantum state to be detected, the number of times of the needed quantum experiment is shown as follows: (2M + 1). times.K. For the reconstruction of some quantum states, such as the evolution state of a multi-body quantum system, the first preset number M is set to be very small, so that the complexity of the whole reconstruction process does not show exponential increase, the complexity of reconstruction is effectively reduced, and the reconstruction efficiency is improved.
It should be noted that the quantum state reconstruction method provided in this embodiment may also be applied to initialization or diagonalization of a quantum state to be measured, for example, a preset quantum state is set as a diagonal matrix, so that the quantum state to be measured can be driven into the diagonal matrix, and thus diagonalization of the quantum state to be measured is achieved.
According to the technical scheme of the embodiment, quantum state reconstruction is carried out by mixing quantum computing equipment and classical computing equipment, in the quantum state reconstruction process, the step that the reconstruction complexity increases exponentially along with the increase of the number of quantum bits is executed by the quantum computing equipment, and the step that the reconstruction complexity does not increase exponentially along with the increase of the number of quantum bits is executed by the classical computing equipment, so that the reconstruction complexity can be reduced by means of quantum computing. Specifically, the quantum computing device determines the quantum state similarity between the current quantum state and the preset quantum state by applying the current pulse sequence in the quantum state to be tested in the quantum system, and sends the quantum state similarity to the classical computing device, the classical computing device determines whether the current pulse sequence drives the quantum state to be tested to the preset quantum state according to the quantum state similarity, if so, reconstructs the quantum state to be tested according to the current pulse sequence, otherwise, a gradient information acquisition request needs to be sent, so that the quantum computing device determines the gradient information corresponding to the quantum state similarity and sends the gradient information to the classical computing device, the classical computing device can update the current pulse sequence according to the gradient information and send the updated current pulse sequence to the quantum computing device, so that the quantum computing device reapplies the updated current pulse sequence, and sequentially circulating until the quantum state to be detected is driven to the preset quantum state and the quantum state to be detected is reconstructed, so that the reconstruction complexity of the quantum state can be prevented from increasing exponentially, and the reconstruction efficiency of the quantum state is effectively improved.
Example two
Fig. 2 is a flowchart of a quantum state reconstruction method according to a second embodiment of the present invention, which is applicable to a case of determining an unknown quantum state in a quantum system. The method may be performed by a quantum state reconstruction apparatus integrated in a classical computing device, which apparatus may be implemented by means of software and/or hardware. As shown in fig. 2, the method specifically includes the following steps:
and S210, when a reconstruction starting instruction is detected, sending the initial pulse sequence as a current pulse sequence to the quantum computing equipment.
The reconstruction starting instruction may be used to characterize an instruction to start performing a quantum state reconstruction operation, and may be generated by a user's trigger operation. The initial pulse sequence may refer to a pulse sequence applied for the first time on a quantum state to be measured of the quantum system.
Specifically, the user may trigger the operation for generating the reconstruction start instruction by clicking or touching a button on a display interface of a classic computing device, so as to generate the reconstruction start instruction. When detecting the generated reconstruction starting instruction, the classical computing device may send an initial pulse sequence generated randomly as a current pulse sequence to the quantum computing device, so that the quantum computing device applies the initial pulse sequence to a quantum state to be measured of the quantum system for the first time to perform a quantum experiment.
S220, when the quantum state similarity sent by the quantum computing equipment is received and the quantum state similarity is detected to be larger than or equal to the preset similarity, reconstructing the quantum state to be detected in the quantum system according to the current pulse sequence and the preset quantum state.
The preset similarity may be preset and used to represent the corresponding similarity when the quantum state to be detected is driven to the preset quantum state.
Specifically, when the classical computing device receives the quantum state similarity sent by the quantum computing device, the classical computing device may determine whether the current pulse sequence drives the quantum state to be detected to the preset quantum state in a manner of comparing the quantum state similarity with the preset similarity. If the quantum state similarity is greater than or equal to the preset similarity, it is indicated that the current quantum state is consistent with the preset quantum state, and the current pulse sequence is an optimal pulse sequence to drive the quantum state to be tested to the preset quantum state, and at this time, the current pulse sequence C and the preset quantum state rho can be used for driving the quantum state to be tested to the preset quantum stateaAnd reconstructing the quantum state to be detected, so that all unknown elements in the quantum state to be detected can be reconstructed at one time based on the current pulse sequence, and the reconstruction efficiency is improved.
For example, the "reconstructing the quantum state to be measured in the quantum system according to the current pulse sequence and the preset quantum state" in S220 may include: and multiplying the inverse sequence of the current pulse sequence by the preset quantum state, multiplying the multiplication result by the current pulse sequence again, and determining the obtained multiplication result again as the reconstruction result of the quantum state to be detected in the quantum system. Specifically, the classical computing device can simulate a quantum state reconstruction process, and mathematically, the current pulse sequence, the preset quantum state and the inverse sequence of the current pulse sequence can all be represented as a matrix in a square matrix form, so that the quantum state to be reconstructed can be reconstructed in a matrix multiplication manner, that is, the reconstructed quantum state to be measured can be represented as:
and S230, when the quantum state similarity is detected to be smaller than the preset similarity, sending a gradient information acquisition request to the quantum computing equipment, updating the current pulse sequence according to the received gradient information, and sending the updated current pulse sequence to the quantum computing equipment.
The gradient information acquisition request may refer to a message for requesting acquisition of gradient information. The gradient information can be used for reflecting the variation of the quantum state similarity of the current pulse sequence, so that the current pulse sequence can be reasonably and accurately updated based on the gradient information, the current pulse sequence capable of driving the quantum state to be tested to the preset quantum state can be obtained as soon as possible, and the reconstruction efficiency is further improved.
Specifically, when detecting that the quantum state similarity is smaller than the preset similarity, the classical computing device indicates that the current pulse sequence is not an optimal pulse sequence and cannot drive the quantum state to be detected to the preset quantum state, so that an updating operation of the current pulse sequence is required to obtain the current pulse sequence driving the quantum state to be detected to the preset quantum state, at this time, a gradient information acquisition request can be sent to the quantum computing device, so that the quantum computing device determines gradient information corresponding to the quantum state similarity according to the current pulse sequence, and when receiving the gradient information sent by the quantum computing device, the classical computing device can accurately and reasonably update the current pulse sequence according to the gradient information and send the updated current pulse sequence to the quantum computing device, so that the quantum computing device can re-execute the quantum state similarity determination operation based on the updated current pulse sequence, until the classical computing equipment reconstructs the quantum state to be detected when detecting that the similarity of the received quantum state is greater than the preset similarity.
Illustratively, the gradient information includes gradient information corresponding to each slice parameter in the current pulse sequence; accordingly, the "updating the current pulse sequence according to the received gradient information" in S230 may include: determining an updating interval corresponding to each fragment parameter according to a preset updating step length and gradient information corresponding to each fragment parameter in the current pulse sequence; and updating each fragment parameter in the current pulse sequence according to the updating interval, and determining the updated current pulse sequence.
When the current pulse sequence is a parameterized pulse sequence c (b), dividing the parameter b in the current pulse sequence c (b) into a first preset number of slice parameters, where each slice parameter corresponds to an x direction and a y direction, that is, the parameter b may be mathematically expressed as:
b＝{bx[1],bx[2],...bx[M],by[1],by[2],...by[M]}
wherein M is a first predetermined number. The parameter b may be composed of M slicing parameters b in the x directionxAnd M slicing parameters b in the y directionyAnd (4) forming. The gradient information received in this embodiment may include gradient information corresponding to 2M slice parameters.
The preset update step may be a change degree for adjusting each slice parameter. The preset updating step length may be fixed or gradually decreased with the increase of the updating times, so that an optimal current pulse sequence may be obtained quickly, i.e., the current pulse sequence corresponding to the preset quantum state is driven by the quantum state to be detected. The update interval may refer to a value added to each slice parameter.
Specifically, for each slice parameter in the current pulse sequence, a multiplication result of the gradient information corresponding to each slice parameter and the preset update step may be determined as an update interval corresponding to the slice parameter. And adding the updating interval corresponding to the fragment parameter with the current value corresponding to the fragment parameter in the current pulse sequence, determining the obtained addition result as the updated parameter value of the fragment parameter, and similarly, updating each fragment parameter in the current pulse sequence so as to obtain the updated current sequence pulse. Exemplarily, the m-th slice parameter b in the x-direction in the current pulse sequencex[m]The update process of (a) can be expressed as:
where k is the current number of updates,
is the value of the m-th slicing parameter in the x direction in the current burst sequence obtained at the kth time;
is a preset update step length used at the kth time;
the gradient value corresponding to the mth slicing parameter in the x direction in the current dash sequence obtained at the kth time;
is the value of the m-th slice parameter in the x direction in the current burst sequence obtained at the (k +1) th time, i.e. the pair
The value obtained after updating.
According to the technical scheme of the embodiment, quantum state reconstruction is carried out by mixing quantum computing equipment and classical computing equipment, in the quantum state reconstruction process, the step that the reconstruction complexity increases exponentially along with the increase of the number of quantum bits is executed by the quantum computing equipment, and the step that the reconstruction complexity does not increase exponentially along with the increase of the number of quantum bits is executed by the classical computing equipment, so that the reconstruction complexity can be reduced by means of quantum computing. Specifically, the quantum computing device determines the quantum state similarity between the current quantum state and the preset quantum state by applying the current pulse sequence in the quantum state to be tested in the quantum system, and sends the quantum state similarity to the classical computing device, the classical computing device determines whether the current pulse sequence drives the quantum state to be tested to the preset quantum state according to the quantum state similarity, if so, reconstructs the quantum state to be tested according to the current pulse sequence, otherwise, a gradient information acquisition request needs to be sent, so that the quantum computing device determines the gradient information corresponding to the quantum state similarity and sends the gradient information to the classical computing device, the classical computing device can update the current pulse sequence according to the gradient information and send the updated current pulse sequence to the quantum computing device, so that the quantum computing device reapplies the updated current pulse sequence, and sequentially circulating until the quantum state to be detected is driven to the preset quantum state and the quantum state to be detected is reconstructed, so that the reconstruction complexity of the quantum state can be prevented from increasing exponentially, and the reconstruction efficiency of the quantum state is effectively improved.
The following is an embodiment of a quantum state reconstruction device provided in an embodiment of the present invention, and the device and the quantum state reconstruction method of the first embodiment belong to the same inventive concept, and details that are not described in detail in the embodiment of the quantum state reconstruction device may refer to the description of the quantum state reconstruction method in the first embodiment.
EXAMPLE III
Fig. 3 is a schematic structural diagram of a quantum state reconstruction apparatus provided in a third embodiment of the present invention, where this embodiment is applicable to a case of determining an unknown quantum state in a quantum system, and the apparatus is integrated in a quantum computing device, and specifically includes: a current pulse sequence applying module 310, a quantum state similarity determining module 320, and a gradient information determining module 330.
The current pulse sequence applying module 310 is configured to apply a current pulse sequence to a quantum state to be detected in a quantum system when receiving the current pulse sequence sent by a classical computing device, and acquire quantum experimental data corresponding to the current quantum state; the quantum state similarity determining module 320 is configured to determine a quantum state similarity between a current quantum state and a preset quantum state according to quantum experimental data, and send the quantum state similarity to a classical computing device, so that the classical computing device reconstructs a quantum state to be detected according to the quantum state similarity, or sends a gradient information obtaining request; the gradient information determining module 330 is configured to determine, when a gradient information obtaining request is received, gradient information corresponding to the quantum state similarity according to the current pulse sequence, and send the gradient information to the classical computing device, so that the classical computing device updates the current pulse sequence according to the gradient information.
Optionally, the quantum state is preset to be a quantum-based vector state; accordingly, the quantum state similarity determining module 320 is specifically configured to: and acquiring the projection probability of the current quantum state in the quantum experimental data on the quantum basis state, and determining the projection probability as the quantum state similarity between the current quantum state and the quantum basis failure state.
Optionally, the current pulse sequence includes a first preset number of sliced pulse sequences, where the first preset number is predetermined according to the number of quantum bits in the quantum system; the slicing pulse sequence is obtained by dividing parameters of the current pulse sequence, and the rotation direction of each bit in the slicing pulse sequence includes an x direction and a y direction.
Optionally, the gradient information determining module 330 is specifically configured to:
according to a preset gradient step length, adjusting each slicing parameter in the current pulse sequence one by one to obtain a second preset number of target pulse sequences, wherein the second preset number is twice of the first preset number; applying each target pulse sequence to a quantum state to be detected in a quantum system one by one to obtain target experimental data, and determining target similarity corresponding to each target pulse sequence according to the target experimental data; and determining the gradient information corresponding to each fragment parameter in the current pulse sequence according to the quantum state similarity, the target similarities and the preset gradient step length.
The quantum state reconstruction device provided by the embodiment of the invention can execute the quantum state reconstruction method provided by the embodiment of the invention, and has the corresponding functional modules and beneficial effects of executing the quantum state reconstruction method.
The following is an embodiment of a quantum state reconstruction device provided in an embodiment of the present invention, which belongs to the same inventive concept as the quantum state reconstruction method of the second embodiment, and reference may be made to the description of the quantum state reconstruction method of the second embodiment for details that are not described in detail in the embodiment of the quantum state reconstruction device.
Example four
Fig. 4 is a schematic structural diagram of a quantum state reconstruction apparatus according to a fourth embodiment of the present invention, where this embodiment is applicable to a case of determining an unknown quantum state in a quantum system, and the apparatus is integrated in a classical computing device, and specifically includes: an initial pulse sequence sending module 410, a quantum state reconstruction module 420 and a current pulse sequence updating module 430.
The initial pulse sequence sending module 410 is configured to, when a reconstruction start instruction is detected, send the initial pulse sequence as a current pulse sequence to the quantum computing device; the quantum state reconstruction module 420 is configured to reconstruct a to-be-detected quantum state in the quantum system according to the current pulse sequence and a preset quantum state when the quantum state similarity sent by the quantum computing device is received and the quantum state similarity is detected to be greater than or equal to the preset similarity; and a current pulse sequence updating module 430, configured to send a gradient information acquisition request to the quantum computing device when detecting that the quantum state similarity is smaller than the preset similarity, update the current pulse sequence according to the received gradient information, and send the updated current pulse sequence to the quantum computing device.
Optionally, the quantum state reconstruction module 420 is specifically configured to: and multiplying the inverse sequence of the current pulse sequence by the preset quantum state, multiplying the multiplication result by the current pulse sequence again, and determining the obtained multiplication result again as the reconstruction result of the quantum state to be detected in the quantum system.
Optionally, the gradient information includes gradient information corresponding to each slice parameter in the current pulse sequence; accordingly, the current pulse sequence updating module 430 is specifically configured to: determining an updating interval corresponding to each fragment parameter according to a preset updating step length and gradient information corresponding to each fragment parameter in the current pulse sequence; and updating each fragment parameter in the current pulse sequence according to the updating interval, and determining the updated current pulse sequence.
The quantum state reconstruction device provided by the embodiment of the invention can execute the quantum state reconstruction method provided by the second embodiment of the invention, and has the corresponding functional modules and beneficial effects of executing the quantum state reconstruction method.
EXAMPLE five
Fig. 5 is a schematic structural diagram of a quantum state reconstruction system according to a fifth embodiment of the present invention, where this embodiment is applicable to a case of determining an unknown quantum state in a quantum system, and the system includes: quantum computing device 510 and classical computing device 520. Quantum computing device 510 and classical computing device 520 may be wired or wireless connected in advance, among other things, so that communication may be performed to transfer information.
Illustratively, the working process of the quantum state reconstruction system is as follows: when detecting a reconstruction start instruction, classical computing device 520 sends the initial pulse sequence as a current pulse sequence to quantum computing device 510; the quantum computing device 510 applies the current pulse sequence to the quantum state to be tested in the quantum system, obtains quantum experimental data corresponding to the current quantum state, determines the quantum state similarity between the current quantum state and the preset quantum state according to the quantum experimental data, and sends the quantum state similarity to the classical computing device 520; when detecting that the similarity of the quantum state is greater than or equal to the preset similarity, the classical computing device 520 reconstructs the quantum state to be detected according to the current pulse sequence and the preset quantum state; when detecting that the quantum state similarity is smaller than the preset similarity, the vector sub-computing device 510 sends a gradient information acquisition request; when receiving the gradient information acquisition request, the quantum computing device 510 determines the gradient information corresponding to the quantum state similarity according to the current pulse sequence, and sends the gradient information to the classical computing device 520; classical computing device 520 updates the current pulse sequence based on the received gradient information and sends the updated current pulse sequence to quantum computing device 510. And sequentially and circularly executing until the classical computing equipment 520 reconstructs the quantum state to be detected when detecting that the similarity of the received quantum state is greater than the preset similarity.
Optionally, when the preset quantum state is the quantum base state, the quantum computing device 510 may further obtain a projection probability of the current quantum state in the quantum experimental data on the quantum base state, and determine the projection probability as a quantum state similarity between the current quantum state and the quantum base failure state.
Optionally, the quantum computing device 510 may further adjust each slice parameter in the current pulse sequence one by one according to a preset gradient step size, to obtain a second preset number of target pulse sequences, where the second preset number is twice as large as the first preset number; applying each target pulse sequence to a quantum state to be detected in a quantum system one by one to obtain target experimental data, and determining target similarity corresponding to each target pulse sequence according to the target experimental data; and determining the gradient information corresponding to each fragment parameter in the current pulse sequence according to the quantum state similarity, the target similarities and the preset gradient step length.
Optionally, the classical computing device 520 may further multiply the inverse sequence of the current pulse sequence by a preset quantum state, multiply the multiplication result by the current pulse sequence again, and determine the obtained multiplication result again as a reconstruction result of the quantum state to be measured in the quantum system.
Optionally, when the gradient information includes gradient information corresponding to each slice parameter in the current pulse sequence, the classical computing device 520 may further determine an update interval corresponding to each slice parameter according to a preset update step length and the gradient information corresponding to each slice parameter in the current pulse sequence; and updating each fragment parameter in the current pulse sequence according to the updating interval, and determining the updated current pulse sequence.
In the quantum state reconstruction system in this embodiment, quantum state reconstruction is performed by using a mixture of quantum computing equipment and classical computing equipment, and in the quantum state reconstruction process, the step of increasing the reconstruction complexity exponentially with the increase of the number of quantum bits is performed by the quantum computing equipment, and the step of increasing the reconstruction complexity exponentially without the increase of the number of quantum bits is performed by the classical computing equipment, so that the reconstruction complexity can be reduced by using a quantum computing method, the reconstruction complexity of the quantum state can be prevented from increasing exponentially, and the reconstruction efficiency of the quantum state is effectively improved.
EXAMPLE six
A sixth embodiment provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the quantum state reconstruction method according to the first embodiment or the second embodiment of the present invention.
Computer storage media for embodiments of the invention may employ any combination of one or more computer-readable media. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. The computer-readable storage medium may be, for example but not limited to: an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.
A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated data signal may take many forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may also be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.
Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to: wireless, wire, fiber optic cable, RF, etc., or any suitable combination of the foregoing.
Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet service provider).
It will be understood by those skilled in the art that the modules or steps of the invention described above may be implemented by a general purpose computing device, they may be centralized on a single computing device or distributed across a network of computing devices, and optionally they may be implemented by program code executable by a computing device, such that it may be stored in a memory device and executed by a computing device, or it may be separately fabricated into various integrated circuit modules, or it may be fabricated by fabricating a plurality of modules or steps thereof into a single integrated circuit module. Thus, the present invention is not limited to any specific combination of hardware and software.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (16)
1. A quantum state reconstruction method applied to a quantum computing device comprises the following steps:
when a current pulse sequence sent by classical computing equipment is received, applying the current pulse sequence to a quantum state to be tested in a quantum system to obtain quantum experimental data corresponding to the current quantum state;
determining the quantum state similarity between the current quantum state and a preset quantum state according to the quantum experimental data, and sending the quantum state similarity to the classical computing equipment so that the classical computing equipment reconstructs the quantum state to be tested according to the quantum state similarity or sends a gradient information acquisition request;
when the gradient information acquisition request is received, determining the gradient information corresponding to the quantum state similarity according to the current pulse sequence, and sending the gradient information to the classical computing equipment, so that the classical computing equipment updates the current pulse sequence according to the gradient information.
2. The method of claim 1, wherein the predetermined quantum state is a quantum-based state;
correspondingly, determining the quantum state similarity between the current quantum state and a preset quantum state according to the quantum experimental data comprises:
and acquiring the projection probability of the current quantum state in the quantum experimental data on the quantum basis state, and determining the projection probability as the quantum state similarity between the current quantum state and the quantum basis failure state.
3. The method of claim 1, wherein the current pulse sequence comprises a first preset number of sliced pulse sequences, wherein the first preset number is predetermined according to the number of quantum bits in the quantum system; the slicing pulse sequence is obtained by dividing parameters of the current pulse sequence, and the rotation direction of each bit in the slicing pulse sequence includes an x direction and a y direction.
4. The method of claim 3, wherein determining the gradient information corresponding to the quantum state similarity according to the current pulse sequence comprises:
according to a preset gradient step length, adjusting each slicing parameter in the current pulse sequence one by one to obtain a second preset number of target pulse sequences, wherein the second preset number is twice of the first preset number;
applying each target pulse sequence to a quantum state to be detected in a quantum system one by one to obtain target experimental data, and determining target similarity corresponding to each target pulse sequence according to the target experimental data;
and determining the gradient information corresponding to each fragment parameter in the current pulse sequence according to the quantum state similarity, the target similarities and the preset gradient step length.
5. A quantum state reconstruction method is applied to a classical computing device and comprises the following steps:
when a reconstruction starting instruction is detected, sending the initial pulse sequence serving as a current pulse sequence to quantum computing equipment;
when the quantum state similarity sent by the quantum computing equipment is received and the quantum state similarity is detected to be greater than or equal to the preset similarity, reconstructing the quantum state to be detected in the quantum system according to the current pulse sequence and the preset quantum state;
and when detecting that the quantum state similarity is smaller than the preset similarity, sending a gradient information acquisition request to the quantum computing equipment, updating the current pulse sequence according to the received gradient information, and sending the updated current pulse sequence to the quantum computing equipment.
6. The method of claim 5, wherein reconstructing the quantum state to be measured in the quantum system according to the current pulse sequence and the preset quantum state comprises:
and multiplying the inverse sequence of the current pulse sequence by the preset quantum state, multiplying the multiplication result by the current pulse sequence again, and determining the obtained multiplication result again as the reconstruction result of the quantum state to be detected in the quantum system.
7. The method of claim 5, wherein the gradient information comprises gradient information corresponding to each slice parameter in a current pulse sequence;
accordingly, updating the current pulse sequence according to the received gradient information includes:
determining an updating interval corresponding to each fragment parameter according to a preset updating step length and gradient information corresponding to each fragment parameter in the current pulse sequence;
and updating each fragment parameter in the current pulse sequence according to the updating interval, and determining the updated current pulse sequence.
8. A quantum state reconstruction device, integrated in a quantum computing apparatus, comprising:
the current pulse sequence applying module is used for applying the current pulse sequence to a quantum state to be tested in the quantum system when receiving the current pulse sequence sent by the classical computing equipment, and acquiring quantum experimental data corresponding to the current quantum state;
the quantum state similarity determining module is used for determining the quantum state similarity between the current quantum state and a preset quantum state according to the quantum experimental data and sending the quantum state similarity to the classical computing equipment so that the classical computing equipment reconstructs the quantum state to be tested according to the quantum state similarity or sends a gradient information obtaining request;
and the gradient information determining module is used for determining the gradient information corresponding to the quantum state similarity according to the current pulse sequence when the gradient information acquiring request is received, and sending the gradient information to the classical computing equipment so that the classical computing equipment updates the current pulse sequence according to the gradient information.
9. The apparatus of claim 8, wherein the predetermined quantum state is a quantum-based state; correspondingly, the quantum state similarity determining module is specifically configured to:
and acquiring the projection probability of the current quantum state in the quantum experimental data on the quantum basis state, and determining the projection probability as the quantum state similarity between the current quantum state and the quantum basis failure state.
10. The apparatus of claim 8, wherein the current pulse sequence comprises a first preset number of sliced pulse sequences, wherein the first preset number is predetermined according to the number of quantum bits in the quantum system; the slicing pulse sequence is obtained by dividing parameters of the current pulse sequence, and the rotation direction of each bit in the slicing pulse sequence includes an x direction and a y direction.
11. The apparatus of claim 10, wherein the gradient information determining module is specifically configured to:
according to a preset gradient step length, adjusting each slicing parameter in the current pulse sequence one by one to obtain a second preset number of target pulse sequences, wherein the second preset number is twice of the first preset number;
applying each target pulse sequence to a quantum state to be detected in a quantum system one by one to obtain target experimental data, and determining target similarity corresponding to each target pulse sequence according to the target experimental data;
and determining the gradient information corresponding to each fragment parameter in the current pulse sequence according to the quantum state similarity, the target similarities and the preset gradient step length.
12. A quantum state reconstruction apparatus, integrated in a classical computing device, comprising:
the initial pulse sequence sending module is used for sending the initial pulse sequence serving as a current pulse sequence to the quantum computing equipment when a reconstruction starting instruction is detected;
the quantum state reconstruction module is used for reconstructing a quantum state to be detected in a quantum system according to a current pulse sequence and a preset quantum state when the quantum state similarity sent by the quantum computing equipment is received and the quantum state similarity is detected to be greater than or equal to the preset similarity;
and the current pulse sequence updating module is used for sending a gradient information acquisition request to the quantum computing equipment when detecting that the quantum state similarity is smaller than the preset similarity, updating the current pulse sequence according to the received gradient information, and sending the updated current pulse sequence to the quantum computing equipment.
13. The apparatus of claim 12, wherein the quantum state reconstruction module is specifically configured to:
and multiplying the inverse sequence of the current pulse sequence by the preset quantum state, multiplying the multiplication result by the current pulse sequence again, and determining the obtained multiplication result again as the reconstruction result of the quantum state to be detected in the quantum system.
14. The apparatus of claim 12, wherein the gradient information comprises gradient information corresponding to each slice parameter in a current pulse sequence; correspondingly, the current pulse sequence updating module is specifically configured to:
determining an updating interval corresponding to each fragment parameter according to a preset updating step length and gradient information corresponding to each fragment parameter in the current pulse sequence;
and updating each fragment parameter in the current pulse sequence according to the updating interval, and determining the updated current pulse sequence.
15. A quantum state reconstruction system, comprising a quantum computing device and a classical computing device; wherein the content of the first and second substances,
the quantum computing device is for implementing the quantum state reconstruction method of any one of claims 1-4;
the classical computing device is for implementing the quantum state reconstruction method of any one of claims 5-7.
16. A computer-readable storage medium, on which a computer program is stored, which program, when being executed by a processor, is adapted to carry out the method for quantum state reconstruction according to any one of claims 1-7.
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