CN216795005U - Phase encoding device for quantum communication and quantum communication apparatus - Google Patents
Phase encoding device for quantum communication and quantum communication apparatus Download PDFInfo
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- CN216795005U CN216795005U CN202221014671.XU CN202221014671U CN216795005U CN 216795005 U CN216795005 U CN 216795005U CN 202221014671 U CN202221014671 U CN 202221014671U CN 216795005 U CN216795005 U CN 216795005U
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Abstract
The present invention provides a phase encoding device for quantum communication and a quantum communication apparatus, the phase encoding device including: a first light source; a second light source; a third light source; a fourth light source; a first unequal arm interferometer optically connected to the first light source and the second light source; a second unequal arm interferometer optically connected to the third light source and the fourth light source; a phase modulator disposed on the long arm of the second unequal-arm interferometer; the controller performs phase encoding based on a first phase difference or a second phase difference formed based on phase changes of the optical pulse at the beam splitter and the beam combiner of the first unequal arm interferometer, and performs phase encoding based on a third phase difference or a fourth phase difference formed based on phase changes of the optical pulse at the beam splitter and the beam combiner of the second unequal arm interferometer and a phase difference caused by the phase modulation voltage. The utility model can provide four phase codes required by the system under the condition that the light source does not need to be switched and the phase modulator only needs to load one phase modulation voltage.
Description
Technical Field
The present invention relates to the field of quantum communication technology, and in particular, to a phase encoding device for quantum communication and a quantum communication apparatus including the phase encoding device.
Background
Currently, in a quantum communication system, a phase encoding device as shown in fig. 1 is generally used to implement phase encoding. In the phase encoding apparatus shown in fig. 1, an unequal arm interferometer is mainly used to divide an optical pulse generated by a single light source X into two optical pulses in tandem, and then four different phase differences of 0, pi/2, 3 pi/2, and pi are modulated between the two pulses by a phase modulator PM to encode and carry information. In other words, the phase modulator PM must be able to load and repeatedly switch back and forth between four different phase modulation voltages in order to achieve phase encoding.
However, the phase modulator needs to modulate the rising edge and the flat region of the pulse of the phase modulation voltage every time the phase modulator switches, and this way of repeatedly switching the phase modulation voltage not only causes the phase modulation voltage loaded by the phase modulator to be unstable, but also causes the precision of the modulated phase difference to be poor, thereby reducing the code rate of the system.
SUMMERY OF THE UTILITY MODEL
The utility model aims to provide a phase encoding device for quantum communication and a quantum communication device.
According to an aspect of the present invention, there is provided a phase encoding device for quantum communication, the phase encoding device comprising: a first light source; a second light source; a third light source; a fourth light source; a first unequal arm interferometer optically connected to the first light source and the second light source for splitting the light pulses output by the first light source and the second light source into a first path of sub light pulses and a second path of sub light pulses which are adjacent in time; a second unequal arm interferometer optically connected to the third and fourth light sources for splitting the light pulses output by the third and fourth light sources into temporally adjacent third and fourth sub light pulses; a phase modulator provided on a long arm of the second unequal arm interferometer for applying a phase modulation voltage to the long arm; and a controller electrically connected to the first light source, the second light source, the third light source, and the fourth light source, for performing the following operations: phase-encoding according to a first phase difference or a second phase difference formed between the first sub optical pulse and the second sub optical pulse based on a phase change of the first sub optical pulse and the second sub optical pulse on a beam splitter and a beam combiner of the first unequal arm interferometer when the optical pulses are output via the first light source or the second light source, and phase-encoding according to a third phase difference or a fourth phase difference formed between the third sub optical pulse and the fourth sub optical pulse based on a phase change of the third sub optical pulse and the fourth sub optical pulse on a beam splitter and a beam combiner of the second unequal arm interferometer and a phase difference caused by the phase modulation voltage when the optical pulses are output via the third light source or the fourth light source.
Preferably, the phase difference caused by the phase modulation voltage is pi/2.
Preferably, the first phase difference and the second phase difference are pi and 0, respectively, and the third phase difference and the fourth phase difference are 3 pi/2 and pi/2, respectively.
Preferably, the phase encoding device further includes: and an intensity modulator, disposed at an output end of the first unequal arm interferometer and the second unequal arm interferometer, for applying an intensity modulation voltage to the optical pulses output by the first unequal arm interferometer and the second unequal arm interferometer, wherein the controller performs trap state processing on the optical pulses output by the first unequal arm interferometer and the second unequal arm interferometer by the intensity modulation voltage applied by the intensity modulator.
According to another aspect of the present invention, there is provided a quantum communication device comprising the phase encoding apparatus for quantum communication as described above.
The phase coding device and the quantum communication equipment provided by the utility model can provide four phase codes required by a system under the condition that a light source does not need to be switched and the phase modulator only needs to load one phase modulation voltage, so that the problem of unstable phase modulation voltage loaded by the phase modulator due to repeated switching of the phase modulator between four different phase modulation voltages can be effectively avoided, and the code forming rate of the system can be further improved.
Drawings
The above objects and features of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings.
Fig. 1 shows a schematic diagram of a phase encoding apparatus for quantum communication in the related art.
Fig. 2 shows a schematic diagram of the phase encoding apparatus for quantum communication of the present invention.
Fig. 3 shows a schematic diagram of optical pulse modulation for phase encoding using the phase encoding apparatus for quantum communication of the present invention.
Detailed Description
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Referring to fig. 2, the phase encoding apparatus for quantum communication of the present invention may include a light source X0, a light source X1, a light source X2, a light source X3, an unequal arm interferometer M-Z1Interferometer M-Z with unequal arms2A phase modulator PM, and a controller (not shown) such as, but not limited to, a control chip such as an FPGA, MCU, etc.
Phase encoding for quantum communication shown in fig. 2In a code device, unequal arm interferometers M-Z1Optically connectable to light source X0 and light source X1, operable to split the light pulses output by light source X0 and light source X1 into temporally adjacent first and second sub-light pulses; unequal arm interferometer M-Z2Optically connectable to light source X2 and light source X3 operable to split the light pulses output by light source X2 and light source X3 into temporally adjacent third and fourth sub-light pulses; the phase modulator PM can be arranged on an unequal arm interferometer M-Z2Long arm L of3It can be used for the long arm L3Applying a phase modulation voltage; the controller may be electrically connected to the light source X0, the light source X1, the light source X2, and the light source X3, which may be configured to: when outputting a light pulse via one of the light source X0 and the light source X1, the light pulse is based on a first path of sub-light pulses and a second path of sub-light pulses at the unequal arm interferometer M-Z1Beam splitter BS1And combiner BC1The first phase difference or the second phase difference formed between the first sub light pulse and the second sub light pulse is phase-encoded by the phase change, and when the light pulse is outputted via one of the light source X2 and the light source X3, the light pulse is outputted according to the non-equal arm interferometer M-Z based on the third sub light pulse and the fourth sub light pulse2Beam splitter BS2And combiner BC2The third phase difference or the fourth phase difference formed between the third optical sub-pulse and the fourth optical sub-pulse due to the phase change of the third sub-pulse and the phase difference caused by the phase modulation voltage.
In addition, in the phase encoding apparatus for quantum communication shown in fig. 2, an intensity modulator (not shown) may be further included, and the intensity modulator may be disposed at the unequal arm interferometer M-Z1Interferometer with unequal arms M-Z2For an anisometric arm interferometer M-Z1And unequal arm interferometer M-Z2The output light pulse is applied with an intensity modulation voltage, and the controller can apply the intensity modulation voltage to the unequal arm interferometers M-Z through the intensity modulator1And unequal arm interferometer M-Z2The output light pulse is subjected to a decoy state process to further weaken the intensity of the output light pulse.
Next, an optical pulse modulation process using the phase encoding apparatus for quantum communication of the present invention for phase encoding will be described in further detail with reference to fig. 2 and 3.
In the optical pulse modulation process shown in FIG. 3, the controller may direct the unequal arm interferometers M-Z via the light source X01Outputting a light pulse 1010, the light pulse 1010 being output by an unequal arm interferometer M-Z1Split into two sub-optical pulses 1011 and 1012, where the sub-optical pulse 1011 may be obtained from an unequal arm interferometer M-Z1Beam splitter BS1Enters into an unequal arm interferometer M-Z1Long arm L of1And along unequal arm interferometer M-Z1Long arm L of1Transmitted to an unequal arm interferometer M-Z1Combiner BC1Sub-optical pulses 1012 may be obtained from an unequal arm interferometer M-Z1Beam splitter BS1Enters into an unequal arm interferometer M-Z1Short arm L of2And along unequal arm interferometer M-Z1Short arm L of2Transmitted to an unequal arm interferometer M-Z1Combiner BC1. During the transmission process, the phase of sub-optical pulse 1011 is not equal to that of arm interferometer M-Z1Beam splitter BS1And combiner BC1Increases pi by reflection of sub-optical pulse 1012 due to the unequal arm interferometer M-Z1Beam splitter BS1And combiner BC1Without change in transmission. Therefore, the M-Z interferometer can be based on two sub-light pulses 1011 and 1012 at unequal arms1Beam splitter BS1And combiner BC1The phase change in the first sub-optical pulse 1011 and the second sub-optical pulse 1012 form a first phase difference of pi (i.e., phi = pi). Accordingly, the controller may implement phase encoding of the two sub-optical pulses 1011 and 1012 according to the resulting first phase difference pi.
In the optical pulse modulation process shown in FIG. 3, the controller may also direct the non-equal arm interferometer M-Z via the light source X11Outputting a light pulse 1020, the light pulse 1020 being output by an unequal arm interferometer M-Z1Split into two sub-optical pulses 1021 and 1022, where sub-optical pulse 1021 may be derived from an asymmetric arm interferometer M-Z1Beam splitter BS1Enters into an unequal arm interferometer M-Z1Long arm L of1And along unequal arm interferometer M-Z1Long arm L of1Transmitted to an unequal arm interferometer M-Z1Combiner BC1Sub-optical pulses 1022 may be derived from an unequal arm interferometer M-Z1Beam splitter BS1Enters into an unequal arm interferometer M-Z1Short arm L of2And along unequal arm interferometer M-Z1Short arm L of2Transmitted to an unequal arm interferometer M-Z1Combiner BC1. During the transmission process, the phase of sub-optical pulse 1021 is due to the unequal arm interferometers M-Z1Combiner BC1Increases pi/2, the phase of sub-optical pulse 1022 is increased by the non-equal arm interferometer M-Z1Beam splitter BS1Increases by pi/2. Therefore, the interferometer M-Z can be based on two sub-optical pulses 1021 and 10221Beam splitter BS1And combiner BC1The second phase difference of 0 (i.e., phi = 0) is formed between the two sub-light pulses 1021 and 1022. Accordingly, the controller may implement phase encoding of the two sub-optical pulses 1021 and 1022 according to the second phase difference 0 obtained thereby.
In the optical pulse modulation process shown in FIG. 3, the controller may also direct the non-equal arm interferometer M-Z via the light source X22 Outputting light pulse 1030, light pulse 1030 may be processed by an unequal arm interferometer M-Z2Split into two sub-optical pulses 1031 and 1032, where sub-optical pulses 1031 may be obtained from an unequal arm interferometer M-Z2Beam splitter BS2Enters into an unequal arm interferometer M-Z2Long arm L of3And along unequal arm interferometer M-Z2Long arm L of3Transmission to the unequal arm interferometer M-Z via the phase modulator PM2Combiner BC2Sub-optical pulses 1032 may be obtained from an unequal arm interferometer M-Z2Beam splitter BS2Enters into an unequal arm interferometer M-Z2Short arm L of4And along unequal arm interferometer M-Z2Short arm L of4Transmitted to an unequal arm interferometer M-Z2Beam combiner BC2. In the transmission process, the phase of sub-optical pulse 1031 is different from that of arm interferometer M-Z2Beam splitter BS2And beam combinerBC2Increases pi/2 due to the phase difference caused by the phase modulation voltage in addition to increases pi due to the reflection of (2); phase of sub-optical pulse 1032 due to unequal arm interferometer M-Z2Beam splitter BS2And combiner BC2Without changing the transmission. Therefore, the unequal arm interferometer M-Z can be based on two sub-optical pulses 1031 and 10322Beam splitter BS2And combiner BC2The third phase difference 3 pi/2 (i.e., phi =3 pi/2) is formed between the two sub-optical pulses 1031 and 1032 by the phase change of the phase and the phase difference caused by the phase modulation voltage. Accordingly, the controller may implement phase encoding of the two sub-optical pulses 1031 and 1032 according to the resulting third phase difference 3 pi/2.
In addition, in the optical pulse modulation process shown in FIG. 3, the controller may also direct the unequal arm interferometer M-Z via the light source X32 Outputting light pulses 1040, the light pulses 1040 may be processed by an unequal arm interferometer M-Z2Split into two sub-optical pulses 1041 and 1042, where sub-optical pulse 1041 may be derived from an unequal arm interferometer M-Z2Beam splitter BS2Enters into an unequal arm interferometer M-Z2Long arm L of3And along unequal arm interferometer M-Z2Long arm L of3Transmitted to an unequal arm interferometer M-Z via a phase modulator PM2Combiner BC2The sub-optical pulses 1042 may be derived from an unequal arm interferometer M-Z2Beam splitter BS2Enters into an unequal arm interferometer M-Z2Short arm L of4And along unequal arm interferometer M-Z2Short arm L of4Transmitted to an unequal arm interferometer M-Z2Combiner BC2. During the transmission process, the phase of sub-optical pulse 1041 is different from that of sub-optical pulse due to the unequal arm interferometer M-Z2Beam combiner BC2Increases pi/2 due to the phase difference caused by the phase modulation voltage in addition to increases pi/2 due to the reflection of (2); phase of sub-optical pulse 1042 by unequal arm interferometer M-Z2Beam splitter BS2Increases by pi/2. Therefore, two sub-optical pulses 1041 and 1042 may be based on the non-equal arm interferometer M-Z2Beam splitter BS2And combiner BC2Phase change in and phase difference caused by phase modulation voltageAnd a fourth phase difference of pi/2 (i.e., phi = pi/2) is formed between two sub-light pulses 1041 and 1042. Accordingly, the controller may implement phase encoding of the two sub-optical pulses 1041 and 1042 according to the fourth phase difference pi/2 obtained thereby.
It should be understood that although fig. 3 shows a schematic diagram of optical pulse modulation for phase encoding using the phase encoding apparatus for quantum communication of the present invention, the phase encoding process shown in fig. 3 is only schematic. The utility model is not limited thereto.
Furthermore, the present invention can also provide a quantum communication device (such as a transmitting end of a quantum key distribution system) including the phase encoding apparatus for quantum communication of the present invention.
The phase coding device and the quantum communication equipment provided by the utility model can provide four phase codes required by a system under the condition that a light source does not need to be switched and the phase modulator only needs to load one phase modulation voltage, so that the problem of unstable phase modulation voltage loaded by the phase modulator due to repeated switching of the phase modulator between four different phase modulation voltages can be effectively avoided, and the code forming rate of the system can be further improved.
While the present application has been shown and described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made to these embodiments without departing from the spirit and scope of the present application as defined by the following claims.
Claims (5)
1. A phase encoding apparatus for quantum communication, the phase encoding apparatus comprising:
a first light source;
a second light source;
a third light source;
a fourth light source;
a first unequal arm interferometer optically connected to the first light source and the second light source for splitting the light pulses output by the first light source and the second light source into a first path of sub light pulses and a second path of sub light pulses which are adjacent in time;
a second unequal arm interferometer optically connected to the third and fourth light sources for splitting the light pulses output by the third and fourth light sources into temporally adjacent third and fourth sub light pulses;
a phase modulator provided on a long arm of the second unequal arm interferometer for applying a phase modulation voltage to the long arm; and
a controller electrically connected to the first, second, third and fourth light sources for performing the following operations:
performing phase encoding according to a first phase difference or a second phase difference formed between the first path of sub light pulses and the second path of sub light pulses based on phase changes of the first path of sub light pulses and the second path of sub light pulses on a beam splitter and a beam combiner of the first unequal arm interferometer when light pulses are output via the first light source or the second light source,
when the optical pulses are output via the third optical source or the fourth optical source, phase-encoding is performed according to a third phase difference or a fourth phase difference formed between the third optical sub-pulse and the fourth optical sub-pulse based on phase changes of the third optical sub-pulse and the fourth optical sub-pulse on a beam splitter and a beam combiner of the second unequal arm interferometer and a phase difference caused by the phase modulation voltage.
2. The phase encoding device of claim 1, wherein the phase difference caused by the phase modulation voltage is pi/2.
3. The phase encoding device according to claim 2, wherein the first phase difference and the second phase difference are pi and 0, respectively, and the third phase difference and the fourth phase difference are 3 pi/2 and pi/2, respectively.
4. The phase encoding device of claim 1, further comprising:
an intensity modulator disposed at the output ends of the first and second unequal arm interferometers for applying an intensity modulation voltage to the optical pulses output by the first and second unequal arm interferometers,
wherein the controller performs decoy state processing on the light pulses output from the first and second unequal arm interferometers by an intensity modulation voltage applied by the intensity modulator.
5. A quantum communication device, comprising:
a phase encoding device for quantum communication according to any one of claims 1 to 4.
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| CN202221014671.XU CN216795005U (en) | 2022-04-29 | 2022-04-29 | Phase encoding device for quantum communication and quantum communication apparatus |
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| CN202221014671.XU CN216795005U (en) | 2022-04-29 | 2022-04-29 | Phase encoding device for quantum communication and quantum communication apparatus |
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