CN212160649U - Hybrid integrated quantum random number generator based on silica waveguide - Google Patents

Abstract

The technology discloses a silica waveguide-based hybrid integrated quantum random number generator, which comprises a random number optical structure, wherein the random number optical structure comprises a hybrid integrated substrate, a first laser chip, a first detector chip and a PLC waveguide are fixed on the hybrid integrated substrate, a second 50:50 beam splitting module, a waveguide delay module and a second 50:50 beam combining module are arranged on the PLC waveguide, the second 50:50 beam splitting module is connected with the second 50:50 beam combining module through two waveguide light paths, and a waveguide delay module is arranged on one waveguide light path; the PLC waveguide is a silica-on-silicon waveguide. The technology can finally realize the quantum random number generator with low cost, high stability and small volume, thereby promoting the widening and development of the application field of the quantum random number generator.

Description

Hybrid integrated quantum random number generator based on silica waveguide

Technical Field

The technology belongs to the field of quantum random numbers, and particularly relates to a hybrid integrated quantum random number generator based on a silicon dioxide waveguide.

Background

Random numbers are one of the important resources of cryptography, and in both classical cryptography and quantum cryptography, their randomness requirements on random numbers are very strict, and even directly determine the security of most cryptosystems. In addition, random numbers are also used extensively outside of cryptography, and play a very important role in gambling, sample statistics, Monte-Carlo simulations, and in some computing sciences.

At present, the generation methods of random numbers can be divided into two main categories based on the characteristics of the generation method and the output sequence: pseudo-random number generators and physical random number generators. The random number generator can stably output a pseudo-random number sequence at a very fast speed, and the algorithm ensures that the output sequence has certain statistical characteristics. However, since the pseudo random number is generated based on a deterministic algorithm, the source of randomness is only the randomness of the input seed, so that it can be predicted theoretically by performing statistical analysis on the generated random number when it is frequently used.

The physical random numbers are different from each other, and the randomness of the physical random numbers is based on the randomness of non-deterministic objective physical phenomena, including atmospheric noise, electronic noise, circuit jitter and the like, and the random number generators generate random numbers by detecting the results of the physical phenomena. Meanwhile, if the physical phenomena are quantum phenomena, the physical random number generator is changed into a quantum random number generator, and the physical phenomena comprise vacuum fluctuation, phase noise, radiative decay and other equivalent physical processes. Due to quantum mechanical intrinsic randomness of quantum physical process, quantum random numbers are generally considered to have true randomness and cannot be predicted, and the quantum random numbers are an ideal random number generator.

With the introduction of this concept, theoretical and experimental work on quantum random number generators has been greatly developed. However, the existing quantum random number generator is generally based on a separation optical device system, still has the problems of large volume, high power consumption, high price and the like, and is not widely applied to the prior art.

As is known, integrated optics is to integrate optical elements on the same substrate and to realize circuit interconnection through high refractive index optical waveguides, so as to solve the problems of large volume, poor stability, high price and the like of the conventional optical system. At the same time, because the results of active devices such as a laser and a detector cannot be realized on the PLC waveguide, the laser and the detector required by the random number generator need to be combined with the results of the PLC waveguide by a hybrid integration method, so that the design and the manufacture of the quantum random number generator are completed.

Disclosure of Invention

The technical problem to be solved by the technology is to provide a silica waveguide-based hybrid integrated quantum random number generator aiming at the defects of the prior art, and the silica waveguide-based hybrid integrated quantum random number generator can finally realize a quantum random number generator with low cost, high stability and small volume, so that the application field of the quantum random number generator is widened and developed.

In order to achieve the technical purpose, the technical scheme adopted by the technology is as follows:

a silica waveguide-based hybrid integrated quantum random number generator comprises a random number optical structure, wherein the random number optical structure comprises a hybrid integrated substrate, a first laser chip, a first detector chip and a PLC waveguide are fixed on the hybrid integrated substrate, a second 50:50 beam splitting module, a waveguide delay module and a second 50:50 beam combining module are arranged on the PLC waveguide, the second 50:50 beam splitting module is connected with the second 50:50 beam combining module through two waveguide light paths, and a waveguide delay module is arranged on one waveguide light path; the PLC waveguide is a silica-based waveguide;

the light pulse sent by the first laser chip is transmitted into a second 50:50 beam splitting module in the PLC waveguide, one end of the second 50:50 beam splitting module is used for sending the light pulse to a second 50:50 beam combining module through a waveguide delay module on the waveguide optical path, the other end of the second 50:50 beam combining module is used for sending the light pulse to the second 50:50 beam combining module through the waveguide optical path, and the second 50:50 beam combining module is used for combining two received light pulses and then transmitting the combined light pulse to the first detector chip.

As a further improved technical scheme of the technology, the 50:50 beam splitting module two is connected with the 50:50 beam combining module two through two waveguide optical paths, one waveguide optical path is provided with a waveguide delay module, the other waveguide optical path is provided with an equal-arm interferometer, the equal-arm interferometer comprises a 50:50 beam splitting module I and a 50:50 beam combining module I, the 50:50 beam splitting module I is connected with the 50:50 beam combining module I through a waveguide upper arm and a waveguide lower arm respectively, the waveguide upper arm and the waveguide lower arm are the same in length, and a phase adjusting module is arranged on the waveguide upper arm and/or the waveguide lower arm.

As a further improved technical solution of the present technology, a first lens and a second lens are further fixed on the hybrid integrated substrate; the first lens is positioned between the first laser chip and the PLC waveguide, and the second lens is positioned between the PLC waveguide and the first detector chip;

the light pulse emitted by the first laser chip is transmitted to the first lens through a spatial light path, the first lens is used for transmitting the light pulse into the PLC waveguide through the spatial light path, and the light pulse enters the second 50:50 beam splitting module through a waveguide light path in the PLC waveguide; and the 50:50 beam combining module II is used for transmitting the light pulse to the end part of the PLC waveguide through the waveguide optical path, and the light pulse enters the detector chip I through the space optical path and the lens II.

The beneficial effect of this technique does: the technology provides a quantum random number generator structure based on silica-on-silicon waveguide hybrid integration, and by utilizing the structure, the volume, the cost and the power consumption of the conventional quantum random number generator can be reduced, and the application scenes and the commercial application market of the quantum random number generator can be greatly widened.

Drawings

Fig. 1 is a first schematic diagram of a random number optical structure according to an embodiment of the present technology.

FIG. 2 is a schematic diagram of a quantum random number generator according to an embodiment of the present technology.

Fig. 3 is a second schematic diagram of a random number optical structure according to an embodiment of the present technology.

Detailed Description

Embodiments of the present technique are further described below with reference to fig. 1-3:

as shown in fig. 1, the silica waveguide-based hybrid integrated quantum random number generator includes a random number optical structure, the random number optical structure includes a hybrid integrated substrate, a first laser chip, a first detector chip and a PLC waveguide are fixed on the hybrid integrated substrate, and a second 50:50 beam splitting module, a second waveguide delay module and a second 50:50 beam combining module are arranged on the PLC waveguide. The 50:50 beam splitting module II is connected with the 50:50 beam combining module II through two waveguide light paths, and one waveguide light path is provided with a waveguide delay module. The PLC waveguide is a silica-on-silicon waveguide. The waveguide delay module is used for optical delay of optical pulses, is generally a long waveguide structure on a PLC waveguide chip, and controls delay amount by controlling the length of a waveguide. Wherein the light pulse emitted by the first laser chip is used for transmitting into a second 50:50 beam splitting module in the PLC waveguide. One end of the 50:50 beam splitting module is used for sending the optical pulse to the 50:50 beam combining module II through the waveguide delay module on the waveguide optical path, and the other end of the 50:50 beam combining module II is used for sending the optical pulse to the 50:50 beam combining module II through the waveguide optical path. And the 50:50 beam combining module II is used for combining the two received light pulses and transmitting the combined light pulses to the detector chip I.

The hybrid integrated substrate of the embodiment is also fixed with a first lens and a second lens; the first lens is positioned between the first laser chip and the PLC waveguide. And the second lens is positioned between the PLC waveguide and the first detector chip. The first lens is used for transmitting the light pulse into the PLC waveguide through the space light path, and the light pulse enters the second 50:50 beam splitting module through the waveguide light path in the PLC waveguide. And the 50:50 beam combining module II is used for transmitting the light pulse to the end part of the PLC waveguide through the waveguide optical path, and the light pulse enters the detector chip I through the space optical path and the lens II.

As shown in fig. 3, in the random number optical structure of this embodiment, a waveguide delay module is disposed on one waveguide optical path between a second 50:50 beam splitting module and a second 50:50 beam combining module, and an equal-arm interferometer may be further disposed on the other waveguide optical path, where the equal-arm interferometer includes a first 50:50 beam splitting module and a first 50:50 beam combining module, the first 50:50 beam splitting module is connected to the first 50:50 beam combining module through a first waveguide upper arm and a second waveguide lower arm, the lengths of the first waveguide upper arm and the second waveguide lower arm are the same, and a phase adjusting module is disposed on the first waveguide upper arm and/or the second waveguide lower arm.

For fig. 2 and 3, the implementation steps are as follows:

(1) the first laser chip is driven by voltage supplied by the driving circuit module, so that the first laser chip works in a gain open mode and emits a series of phase-independent light pulses.

(2) And the optical pulse of the first laser chip enters the PLC optical waveguide after passing through the first lens and is then transmitted in the optical waveguide. And enters a second 50:50 beam splitting module.

(3) The phase adjusting device comprises a first 50:50 beam splitting module, a phase adjusting module and a second 50: the 50 beam combining modules I form an equal-arm MZ interferometer, and the length of the waveguide delay module is controlled to ensure that the optical paths of optical pulses transmitted to the 50:50 beam combining modules I through the upper waveguide arms and the lower waveguide arms have fixed length difference after the optical pulses are split by the 50:50 beam splitting module. The equal arm MZ is used to adjust the intensity of the light pulses transmitted through the MZ interferometer. The device comprises a 50:50 beam splitting module II, a waveguide delay module, and a 50: the 50 beam combining module II and the above-mentioned equal-arm MZ interferometer together form an unequal-arm MZ interferometer, and the length of the waveguide delay module is controlled to ensure that the optical paths of optical pulses transmitted to the 50:50 beam combining module II through the upper arm and the lower arm have fixed length difference after the optical pulses are split by the 50:50 beam splitting module. The intrinsic optical path difference is generally the period of the light pulse emitted by the laser chip, and also includes an integral multiple of the period, so that the front and back light pulses emitted by the laser chip can interfere with each other.

(4) According to the arm length difference of the unequal arm interferometer, light pulses of the first laser chip participating in interference interfere at the second 50:50 beam combining module, and output light intensity signals are as follows:

where I denotes the output light intensity, I₁And I₂Then represents the intensity of the light pulse participating in the interference, theta₁And theta₂Representing the phase of the preceding and following pulses respectively, the phase is completely random since the phase of the individual light pulses emitted by the laser chip is uncorrelated and since the emission of the light pulses is based on spontaneous emission. The output intensity of the interference result is completely random, and the randomness is quantum randomness because the spontaneous emission phenomenon is a quantum phenomenon.

(5) In such a random number generator, the present embodiment defines the interference visibility as follows:

wherein:

therefore, the method comprises the following steps:

the magnitude of the interference visibility is related to the random number production efficiency of the final random number generator, and V is 1 in the system in the embodiment. However, since the waveguide paths traveled by the pulses involved in the interference are different, the intensity I at the time of the final interference is different₁And I₂In practical situations, there may be deviations, and the embodiment can adjust I by adjusting the phase of the phase adjusting module in the equal-arm MZ interferometer₁And I₂The effect of the intensity, so that the interference visibility remains 1.

(6) The interfered random light intensity signals pass through a 50:50 beam combining module II, pass through a waveguide, enter a detector chip I after being subjected to lens dimerization, the detector chip detects the light intensity of light pulses, transmits a detection analog signal result to an analog-digital conversion module through an electric wire, enters a post-processing module after being converted into a digital signal, runs a pre-prepared post-processing algorithm through the post-processing module, extracts random numbers, and outputs the random number signals through a random number output interface.

The implementation steps of fig. 1 are similar to those of fig. 3, where the first phase adjustment module, 50: the first 50 beam combining modules form an equal-arm MZ interferometer, so that the omission of the equal-arm MZ interferometer is caused, and the random number generation efficiency is reduced probably because the intensity of optical pulses participating in interference cannot be adjusted.

In the optical paths of fig. 1 and 3, the dotted line represents a spatial optical path, and the solid line represents a waveguide optical path. In order to enable the random number generator to work normally, a corresponding external driving circuit module and a post-processing module are also needed in the system, as shown in fig. 2, fig. 2 is a schematic diagram of the overall structure of the quantum random number generator. In fig. 2, the solid lines represent metal lines such as driving lines or data transmission lines.

In fig. 2, the driving circuit module provides driving signals for active devices such as a first laser chip, a first detector chip, a phase adjustment module, and the like in the random number optical structure, the analog-to-digital conversion module converts an analog electrical signal result detected by the first detector chip into a digital signal and then sends the digital signal to the post-processing module, the post-processing module is generally a data processing chip such as an ASIC chip or an FPGA chip, the post-processing module performs post-processing on the received digital signal, and then transmits the generated random number through a random number output interface for a user to use, and the general random number output interface includes common data interfaces such as a network interface, a PCI-e interface, and a USB interface.

In summary, the present technology provides a structure of a quantum random number generator based on silica-on-silicon waveguide hybrid integration, and with the structure, the volume, cost and power consumption of the existing quantum random number generator can be reduced, which is beneficial to greatly widening the use scenario and commercial application market of the quantum random number generator.

The technical scope of the present invention includes, but is not limited to, the above embodiments, the technical scope of the present invention is defined by the claims, and any replacement, modification, and improvement that can be easily conceived by those skilled in the art are included in the technical scope of the present invention.

Claims (3)

1. A hybrid integrated quantum random number generator based on silica waveguides, comprising: the random number optical structure comprises a hybrid integrated substrate, wherein a first laser chip, a first detector chip and a PLC waveguide are fixed on the hybrid integrated substrate, a second 50:50 beam splitting module, a second waveguide delay module and a second 50:50 beam combining module are arranged on the PLC waveguide, the second 50:50 beam splitting module is connected with the second 50:50 beam combining module through two waveguide light paths, and a waveguide delay module is arranged on one waveguide light path; the PLC waveguide is a silica-based waveguide;

the light pulse sent by the first laser chip is transmitted into a second 50:50 beam splitting module in the PLC waveguide, one end of the second 50:50 beam splitting module is used for sending the light pulse to a second 50:50 beam combining module through a waveguide delay module on the waveguide optical path, the other end of the second 50:50 beam combining module is used for sending the light pulse to the second 50:50 beam combining module through the waveguide optical path, and the second 50:50 beam combining module is used for combining two received light pulses and then transmitting the combined light pulse to the first detector chip.

2. The silica waveguide-based hybrid integrated quantum random number generator of claim 1, wherein: the 50:50 beam splitting module two is connected with the 50:50 beam combining module two through two waveguide optical paths, one waveguide optical path is provided with a waveguide delay module, the other waveguide optical path is provided with an equal-arm interferometer, the equal-arm interferometer comprises a 50:50 beam splitting module I and a 50:50 beam combining module I, the 50:50 beam splitting module I is connected with the 50:50 beam combining module I through a waveguide upper arm and a waveguide lower arm respectively, the waveguide upper arm and the waveguide lower arm are the same in length, and a phase adjusting module is arranged on the waveguide upper arm and/or the waveguide lower arm.

3. The silica waveguide-based hybrid integrated quantum random number generator of claim 1 or 2, wherein: a first lens and a second lens are fixed on the hybrid integrated substrate; the first lens is positioned between the first laser chip and the PLC waveguide, and the second lens is positioned between the PLC waveguide and the first detector chip;

the light pulse emitted by the first laser chip is transmitted to the first lens through a spatial light path, the first lens is used for transmitting the light pulse into the PLC waveguide through the spatial light path, and the light pulse enters the second 50:50 beam splitting module through a waveguide light path in the PLC waveguide; and the 50:50 beam combining module II is used for transmitting the light pulse to the end part of the PLC waveguide through the waveguide optical path, and the light pulse enters the detector chip I through the space optical path and the lens II.

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