KR102272597B1 - Device for detecting photon - Google Patents

Abstract

The present invention provides a plurality of single-mode optical waveguides to which a single photon is incident; a plurality of optical delay units connected to each of the plurality of single-mode optical waveguides to delay time for photons; a photon lantern device including a plurality of input terminals connected to the plurality of optical delay units and an output terminal for propagating photons input to the input terminals in a multi-space mode; a multi-mode optical waveguide connected to the output terminal; a single photon detector for detecting photons passing through the multimode optical waveguide; and a time distribution detector for measuring a time distribution of photons detected by the single photon detector.

Description

Photon detection device {DEVICE FOR DETECTING PHOTON}

The embodiment relates to a photon detection device, and more particularly, to a photonic lantern device and a photon detection device using a time-resolved detection technique.

Quantum information technology that utilizes photons, the smallest particles constituting light, as information carriers, has been actively researched and developed recently.

First, quantum communication technology is a technology that uses one or several bits of information for each photon for long-distance communication, and provides a level of security that the existing optical communication system cannot provide. Quantum computation technology, which processes complex information by combining bits on several photons, is being developed to solve problems that are difficult to approach with modern computer technology. The field of quantum measurement/quantum sensing that breaks through the limits is also attracting attention.

The effectiveness of quantum technology based on single-photon control is highly dependent on efficient and uniform photon detection technology along with the problem of efficiently generating photons.

That is, in the case of quantum communication, several single-photon detectors must be operated at the same time for fast information processing, and in particular, quantum computation or quantum sensing requires a much larger number of detectors than the number of photons that must be used simultaneously. Single-photon detectors are expensive equipment by themselves, and in some cases, cryogenic vacuum equipment is required, so increasing the number seriously impairs the practicality of the technology.

Single-photon detectors used in single-photon quantum information/quantum sensing technology can be largely divided into semiconductor-based detectors and superconductor-based detectors. In the case of semiconductor-based devices, if they are manufactured in small quantities, they have relatively economic advantages, but have disadvantages of low efficiency and large noise depending on the operating wavelength. In the case of superconducting-based devices, potentially many devices can be integrated and overall detection performance is poor. Although it has the advantage of being excellent, the overall device is bulky and expensive. As an effort to overcome the limitations of a given detector device by an optical technique, a structure such as a photon number resolving detector using a time multiplexing technique has been proposed, but a large number of detectors have been proposed. There is no known technology that can replace a single detector using an optical structure, and the above-described limitations exist.

An embodiment provides a photon detection device.

In addition, there is provided a photon detection apparatus capable of separately detecting photons propagating in a plurality of separate spatial modes using a minimum single photon detector.

In addition, there is provided a photon detection apparatus with improved resource efficiency by combining several separated spatial modes into one multi-mode optical waveguide and allowing photons from separate spatial modes to reach a single photon detector at separate times.

In addition, by connecting the multimode optical waveguide to a plurality of single photon detectors through an optical splitter and measuring the simultaneous count between the single photon detectors, it is possible to measure not only the state in which photons arrive one by one, but also the state in which multiple photons arrive. A photon detection device is provided.

In addition, there is provided an optical detection device with a high possibility of practical use.

A photon detection apparatus according to an embodiment includes: a plurality of single-mode optical waveguides into which a single photon is incident; a plurality of optical delay units connected to each of the plurality of single-mode optical waveguides to delay time for photons; a photon lantern device including a plurality of input terminals connected to the plurality of optical delay units and an output terminal for propagating photons input to the input terminals in a multi-space mode; a multi-mode optical waveguide connected to the output terminal; a single photon detector for detecting photons passing through the multimode optical waveguide; and a time distribution detector for measuring a time distribution of photons detected by the single photon detector.

The single-mode optical waveguide may be formed of a single-mode optical fiber.

The multi-mode optical waveguide may be formed of a multi-mode optical fiber.

The photonic lantern element may have a taper.

The minimum resolvable time of the time distribution analyzer may be smaller than a minimum delay time difference between the plurality of optical delay units.

The plurality of optical delay units may provide different delay times.

The different delay times may be multiples of the minimum delay time.

A photon detection apparatus according to another embodiment includes a plurality of single-mode optical waveguides into which a single photon is incident; a plurality of optical delay units connected to each of the plurality of single-mode optical waveguides to delay time for photons; a photon lantern device including a plurality of input terminals connected to the plurality of optical delay units and an output terminal for propagating photons input to the input terminals in a multi-space mode; a multi-mode optical waveguide connected to the output terminal; an optical splitter connected to the multi-mode optical waveguide to distribute photons passing through the multi-mode optical waveguide to a plurality of optical distribution output terminals; a plurality of single photon detectors connected to each of the plurality of light distribution output terminals to detect photons; and a time distribution detector for measuring a time distribution of photons detected by the plurality of single photon detectors.

The time distribution detector may measure the simultaneous count of at least one of the plurality of single photon detectors simultaneously detecting photons.

The time distribution detector may measure the time distribution of the simultaneous coefficients.

According to an embodiment, a photon detection apparatus may be implemented.

In addition, it is possible to implement a photon detection apparatus capable of separately detecting photons propagating in several separate spatial modes using a minimum single photon detector.

In addition, it is possible to implement a photon detection device with improved resource efficiency by combining several separated spatial modes into one multimode optical waveguide and allowing photons from separate spatial modes to reach the single photon detector at separate times. .

In addition, by connecting the multimode optical waveguide to a plurality of single photon detectors through an optical splitter and measuring the simultaneous count between the single photon detectors, it is possible to measure not only the state in which photons arrive one by one, but also the state in which multiple photons arrive. A photon detection device can be implemented.

In addition, it is possible to provide a photodetector device with a high possibility of practical use.

Various and advantageous advantages and effects of the present invention are not limited to the above, and will be more easily understood in the course of describing specific embodiments of the present invention.

1 is a conceptual diagram of a photon detection apparatus according to a first embodiment of the present invention;
Figure 2 is an enlarged view of part A in Figure 1,
Figure 3 is an enlarged view of part B in Figure 1,
Figure 4 is an enlarged view of part C in Figure 1,
5 is a diagram for explaining the relationship between a time distribution detector and an optical delay unit;
6 is a conceptual diagram of a photon detection apparatus according to a second embodiment.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated and described in the drawings. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

Terms including an ordinal number such as second, first, etc. may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the second component may be referred to as the first component, and similarly, the first component may also be referred to as the second component. and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being “connected” or “connected” to another component, it is understood that the other component may be directly connected or connected to the other component, but other components may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that no other element is present in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

Hereinafter, the embodiment will be described in detail with reference to the accompanying drawings, but the same or corresponding components are given the same reference numerals regardless of reference numerals, and overlapping descriptions thereof will be omitted.

1 is a conceptual diagram of a photon detection apparatus according to a first embodiment of the present invention, FIG. 2 is an enlarged view of part A in FIG. 1 , FIG. 3 is an enlarged view of part B in FIG. 1 , and FIG. 4 is FIG. It is an enlarged view of part C in Fig. 5 is a view for explaining the relationship between the time distribution detector and the optical delay line.

First, referring to FIG. 1 , the photon detection apparatus according to the first embodiment includes a single-mode optical waveguide 110 , an optical delay unit 120 , a photon lantern element 130 , a multi-mode optical waveguide 140 , and a single photon detector. 150 and a temporal distribution detector 160 .

First, the single-mode optical waveguide 110 may receive single photons PT1, PT2, ??PTm. There may be a plurality of single-mode optical waveguides 110 . In addition, each single-mode optical waveguide 110 may be connected to an input terminal of the photon detection device or function as an input terminal. A photon may be incident on any one of the plurality of single-mode optical waveguides 110 . In addition, several photons may be simultaneously incident on one or more single-mode optical waveguides 110 .

Referring to FIG. 2 , a single photon PT1 may pass through the single-mode optical waveguide 110 . In an embodiment, the single-mode optical waveguide 110 may include a first core CO and a first outer portion CL, and photons may move through the first core CO. In addition, the first outer portion CL may surround the first core CO to protect the first core CO and suppress loss of photons. In addition, the plurality of single-mode optical waveguides 110 may be formed of a single-mode fiber.

Referring back to FIG. 1 , the plurality of single-mode optical waveguides 110 include a first single-mode optical waveguide 110-1, a second single-mode optical waveguide 110-2 to an m-th single-mode optical waveguide 110- m) may be included. In addition, at least one of the plurality of single photons PT1, PT2, ??PTm includes the first single-mode optical waveguide 110-1, the second single-mode optical waveguide 110-2 to the m-th single-mode optical waveguide ( 110-m) may be applied respectively.

The optical delay unit 120 may be connected to each of the plurality of single-mode optical waveguides 110 described above. The optical delay unit 120 may delay a time for a photon. For example, the optical delay unit 120 may be formed by splicing a plurality of optical fibers. Accordingly, the optical delay unit 120 may adjust the delay time of the photons by adjusting the path through which the light passes.

Since the optical delay unit 120 is extended to each of the plurality of single-mode optical waveguides 110 , there may be a plurality of optical delay units 120 . In an embodiment, the optical delay unit 120 may include a first optical delay unit 120-1, a second optical delay unit 120-2 to an mth optical delay unit 120-m.

In this case, the plurality of optical delay units 120 may provide different delay times to the photons. For example, the first optical delay unit 120 - 1 may provide the minimum delay time SFa. Alternatively, the second optical delay unit 120-2 may provide a delay time different from that of the first optical delay unit 120-1, for example, a delay time greater than the minimum delay time SFa. In addition, the mth optical delay unit 120 - m may provide a delay time greater than that of the first optical delay unit 120 - 1 and the second optical delay unit 120 - 2 . With this configuration, photons from the plurality of single-mode optical waveguides 110 serving as input terminals may be temporally divided into a plurality (eg, M).

Also, the optical delay unit 120 may be located in the single-mode optical waveguide 110 . Accordingly, the optical delay unit 120 may also be formed of a single-mode fiber as a single-mode optical waveguide.

The photonic lantern device 130 may include a plurality of input terminals In1 to Inm and an output terminal.

The plurality of input terminals In1 to Inm may be connected to a plurality of optical delay lines. The output terminal may propagate photons input to the input terminals In1 to Inm in a multi-space mode.

The photon lantern device 130 may connect a plurality of single-mode optical waveguides 110 to the multi-mode optical waveguide 140 through an output terminal out. That is, the photon lantern device 130 may propagate a plurality of spatial modes to the multi-mode optical waveguide 140 connected to the output terminal. In other words, the photon lantern element 130 acts as a connecting element connecting a plurality of single-mode optical waveguides and multi-mode optical waveguides. With this configuration, since the photon signal incident through the plurality of single-mode optical waveguides 110 is concentrated on the multi-mode optical waveguide 140, efficiency can be improved.

Referring to FIG. 4 , the photon lantern device 130 may be positioned between the single-mode optical waveguide 110 and the multi-mode optical waveguide 140 to have a taper TP. In other words, the photon lantern device 130 according to the embodiment may be a device to which an optical fiber is tapered, or may be formed of an integrated optics circuit.

1 and 3 , the multi-mode optical waveguide 140 may be connected to an output terminal Out of the photonic lantern device 130 . Accordingly, the photons PT1 , PT2 , and PT3 respectively delayed and moved through the plurality of single-mode optical waveguides 110 may propagate through the multi-mode optical waveguide 140 .

The multi-mode optical waveguide 140 is an optical fiber, and may include an inner second core CO′ and a second outer portion CL′, and a plurality of photons may move through the second core CO′. . In addition, since the second outer part CL' surrounds the second core CO', it is possible to protect the second core CO' and provide a function such as light loss suppression.

In addition, in the present specification, the optical waveguide may be made of an optical fiber, the single-mode optical waveguide 110 is made of a single-mode fiber (SMF), and the multi-mode optical waveguide 140 is made of a multi-mode optical fiber (multi-mode). mode fiber: MMF). In addition, it should be understood that the single-mode optical waveguide may be replaced with a few-mode optical waveguide that propagates only a smaller number of spatial modes than the multi-mode optical fiber.

A single-photon detector (SPD) 150 may be connected to the multi-mode optical waveguide 140 . When a photon is incident, the single photon detector 150 may convert it into an electrical signal and output it.

The single photon detector 150 may include a semiconductor avalanche photodiode device or a superconducting nanowire device, but is not limited thereto.

According to the embodiment, the single photon detector 150 is input through each single-mode optical waveguide 110 and has different delay times through the optical delay unit 120, while the photon lantern device 130 and the multi-mode optical waveguide ( 140) may output the plurality of photons PT1, PT2, ,., PTm as electrical signals.

The time distribution detector 160 may measure the time distribution of the photons detected from the single photon detector 150 , ie, the output electrical signal, and determine the input, that is, the single mode optical waveguide to which the photons are incident.

The time distribution detector 160 may be formed of a combination of a time-to-amplitude converter (TAC) and a multi-channel analyzer (MCA). Furthermore, the time distribution detector 160 may be configured as a time tagger device, and may utilize a counter based on an FPGA circuit.

In addition, the time distribution detector 160 can easily measure the spatial distribution of photons simultaneously incident to M input units (that is, m single-mode optical waveguides) by measuring the time and number of photons output from the reference time. have.

Referring to FIG. 5 , the minimum resolvable time Td of the time distribution detector 160 according to the embodiment may be smaller than the minimum delay time SF in the plurality of optical delay units 120 . Here, the minimum delay time SF will be described based on a minimum value among relative differences between delay times PTL->PTF of the plurality of optical delay units.

Furthermore, the delay time of the plurality of optical delay units may be a multiple of the minimum delay time SF. Accordingly, the photon detection apparatus according to the embodiment can easily and accurately measure the number of photons even if a plurality of photons propagate through a plurality of single-mode optical waveguides at the same time.

6 is a conceptual diagram of a photon detection apparatus according to a second embodiment.

Referring to FIG. 6 , the photon detection apparatus according to the second embodiment includes a single-mode optical waveguide 210 , an optical delay unit 220 , a photon lantern element 230 , a multi-mode optical waveguide 240 , and a single-photon detector 250 . ), a time distribution detector 260 and a light splitter 270 .

The single-mode optical waveguide 210 , the optical delay unit 220 , the photon lantern element 230 , and the multi-mode optical waveguide 240 may be identically applied to the above description.

First, the optical splitter 270 may be connected to the multi-mode optical waveguide 240 . In addition, the optical splitter 270 may be disposed between the multi-mode optical waveguide 240 and the single photon detector 250 .

The optical splitter 270 may distribute the plurality of photons propagating through the multi-mode optical waveguide 240 in a predetermined number (eg, n). For example, the light splitter 270 may include a plurality of light distribution output terminals 271 to 271-n to which the distributed photons are output.

The single photon detector 250 may be plural, to which the above description is applied. Each of the plurality of single photon detectors 250 may be connected to the light splitter 270 . For example, each of the plurality of single photon detectors 250 may be connected to a plurality of light distribution output terminals.

The time distribution detector 260 may be connected to a plurality of single photon detectors 250 to receive electrical signals from each.

The time distribution detector 260 may measure a coincidence count arbitrarily set in the plurality of single photon detectors 250 , and measure the frequency of simultaneous detection within a time within a time window of the coincidence count. That is, the time distribution detector 260 may measure not only the above-described functions but also the number of simultaneous counts by accumulating for a predetermined measurement time. In other words, the time distribution detector can easily detect a case in which several photons propagate through the multimode optical waveguide 240 simultaneously by measuring the simultaneous coefficients between the output signals from the N single photon detectors 250 .

For example, photons input through the plurality of single-mode optical waveguides 210 are temporally separated through the optical delay unit 220 . The distribution of the number of photons incident to the photon detection apparatus can be easily measured according to the simultaneous counting of the output signals output through the light splitter 270 and the plurality of single photon detectors 250 .

For example, even if two photons are simultaneously incident on one single-mode optical waveguide, two single-photon detectors among the single-photon detectors 250-1, 250-2, ??, and 250-n simultaneously detect a photon detection signal (described above). one electrical signal), and the time distribution detector 260 may generate a simultaneous count of two photons. Accordingly, the photon detection apparatus according to the embodiment can easily measure the distribution of the number of photons regardless of the input time and number of photons.

In addition, the time distribution detector 260 may be formed of a field programmable gate array (FPGA)-based electronic circuit.

The term '~ unit' used in this embodiment means software or a hardware component such as a field-programmable gate array (FPGA) or ASIC, and '~ unit' performs certain roles. However, '~part' is not limited to software or hardware. The '~ unit' may be configured to reside on an addressable storage medium or may be configured to refresh one or more processors. Thus, as an example, '~' denotes components such as software components, object-oriented software components, class components, and task components, and processes, functions, properties, and procedures. , subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functions provided in the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. In addition, components and '~ units' may be implemented to play one or more CPUs in a device or secure multimedia card.

In the above, the embodiment has been mainly described, but this is only an example and does not limit the present invention, and those of ordinary skill in the art to which the present invention belongs are not exemplified above in the range that does not depart from the essential characteristics of the present embodiment It will be appreciated that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be implemented by modification. And differences related to such modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

Claims (10)

a plurality of single-mode optical waveguides to which a single photon is incident;
a plurality of optical delay units connected to each of the plurality of single-mode optical waveguides to delay time for photons;
a photon lantern device including a plurality of input terminals connected to the plurality of optical delay units and an output terminal for propagating photons input to the input terminals in a multi-space mode;
a multi-mode optical waveguide connected to the output terminal;
a single photon detector for detecting photons passing through the multimode optical waveguide; and
a time distribution detector for measuring the time distribution of photons detected by the single photon detector;
The minimum resolvable time of the time distribution detector is smaller than a difference in the minimum delay time between the plurality of optical delay units.
According to claim 1,
The single-mode optical waveguide is a photon detection device made of a single-mode optical fiber.
According to claim 1,
The multi-mode optical waveguide is a photon detection device made of a multi-mode optical fiber.
delete delete According to claim 1,
The plurality of optical delay units provide different delay times.
7. The method of claim 6,
The different delay times are multiples of the minimum delay time.
a plurality of single-mode optical waveguides to which a single photon is incident;
a plurality of optical delay units connected to each of the plurality of single-mode optical waveguides to delay time for photons;
a photon lantern device including a plurality of input terminals connected to the plurality of optical delay units and an output terminal for propagating photons input to the input terminals in a multi-space mode;
a multi-mode optical waveguide connected to the output terminal;
an optical splitter connected to the multi-mode optical waveguide to distribute photons passing through the multi-mode optical waveguide to a plurality of optical distribution output terminals;
a plurality of single photon detectors connected to each of the plurality of light distribution output terminals to detect photons; and
a time distribution detector for measuring the time distribution of photons detected by the plurality of single photon detectors;
The minimum resolvable time of the time distribution detector is smaller than a difference in the minimum delay time between the plurality of optical delay units.
9. The method of claim 8,
The time distribution detector is a photon detection device for measuring a simultaneous count of at least one of the plurality of single photon detectors simultaneously detecting photons.
10. The method of claim 9,
The time distribution detector is a photon detection device for measuring the time distribution of the simultaneous coefficient.

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