rus
Issue #2/2023
S. N. Mosentsov, A. V. Losev, V. V. Zavodilenko, A. A. Filyaev, I. D. Pavlov, N. V. Burov
Comparison of Domestic Single Photon Detectors by QRate With the An-alogues by ID Quantique
Comparison of Domestic Single Photon Detectors by QRate With the An-alogues by ID Quantique
DOI: 10.22184/1993-7296.FRos.2023.17.2.134.145
The article is devoted to the comparison of specifications of the single photon detectors manufactured by QRate (Russia) and ID Quantique (Switzerland). Their quantum efficiencies, dark count rates, and afterpulse probabilities have been examined in this work. The test results have showed the interchangeability of detectors and non-compliance of foreign detectors with the declared specifications and demonstrated the potential capacities of domestic development.
The article is devoted to the comparison of specifications of the single photon detectors manufactured by QRate (Russia) and ID Quantique (Switzerland). Their quantum efficiencies, dark count rates, and afterpulse probabilities have been examined in this work. The test results have showed the interchangeability of detectors and non-compliance of foreign detectors with the declared specifications and demonstrated the potential capacities of domestic development.
Теги: id quantique qrate quantum technologies russian production single photon detector детектор одиночных фотонов квантовые технологии российское производство
Comparison of Domestic Single Photon Detectors by QRate With the Analogues by
ID Quantique
S. N. Mosentsov 1, A. V. Losev 2, V. V. Zavodilenko 2, A. A. Filyaev 1, I. D. Pavlov 2, N. V. Burov 1
LLS SC, Saint-Petersburg, Russia
QRate LLC, Moscow, Russia
The article is devoted to the comparison of specifications of the single photon detectors manufactured by QRate (Russia) and ID Quantique (Switzerland). Their quantum efficiencies, dark count rates, and afterpulse probabilities have been examined in this work. The test results have showed the interchangeability of detectors and non-compliance of foreign detectors with the declared specifications and demonstrated the potential capacities of domestic development.
Keywords: single photon detector, quantum technologies, ID Quantique, QRate, Russian production
Article received: 21.01.2023
Article accepted: 14.02.2023
Introduction
The Russian company QRate, a developer and supplier of comprehensive hardware and software solutions for information security using the quantum technologies, together with specialists from LLS SC, have tested the own-produced single photon detectors (SPDs) and those made by ID Quantique (Switzerland) in its own research laboratory.
All SPDs were provided with the coherent states with the statistic value of 0.1 photon/pulse. On average, 10 light pulses received by the SPD correspond to one pulse with 1 photon and nine pulses without any photons. The SPDs under study are designed in such a way that, by using the electronic avalanche gain effect, they generate a current pulse at the output when even a single photon is absorbed by the photosensitive detector area.
The objectives of study included a comparative description of domestic SPDs and foreign analogues and examination of the real specifications of foreign SPDs.
Four models of detectors were used in the tests:
two QRate models:
QRATE-SPD-GEN1-FR and QRATE-SPD-GEN2-FR;
two ID Quantique models:
IDQube-NIR-FR-MMF-LN and ID230.
System design
and operation algorithm
The single photon detectors were tested using a special automated measuring set-up, specially designed to measure the SPD operating parameters. The set-up included the following:
synchronization system;
laser pulse source;
beam splitter system (BS);
system of controlled optical attenuators with the adjustable output power;
tested SPD;
frequency counter;
oscilloscope.
The set-up design provides fir an additional optical adapter (OA) for arranging parallel measurements for two SPDs. All components of this system are controlled by the software developed in the LabVIEW environment.
A functional circuit diagram of an automated measuring set-up for the SPD operational parameters is shown in Fig. 1. Thick black links indicate the contact of two devices using the HF coaxial cables, thin ones indicate the optical fibers. Fig. 2 shows the individual units of the automated measuring set-up for the SPD operational parameters.
The laser pulses and strobe electrical signals are generated in the same frequency grid, and the phase shift between them is controlled by a synchronization system. The synchronization system is a field-programmable gate array (FPGA) used as a reference frequency generator for the high-frequency laser driver and SPD. The relative phase between the laser pulses and the sinusoidal strobe SPD pulses can be varied to achieve the highest possible count rate with the unchanged other parameters. The laser source is a laser diode with a central wavelength of 1550.12 nm, mounted on a driver board (Fig. 3) and configured using the console line on a computer.
Optical pulses from the source are sent to the beam splitter input, where they are split into two components with an intensity in the ratio 97/3. The beam splitter is used in order to be able to control the shape, duration and repetition rate of laser pulses in a low-power optical arm by detecting a part of the power incident on a multiphoton detector. At the input of two series-connected controlled attenuators incident light of much lower intensity. Since the power of light transmitted through the first attenuator can be measured, and the second attenuator has a fixed attenuation ratio, then the output power of laser pulses can be controlled and maintained at about 0.1 photon per pulse. Such a signal enters the SPD input.
The output electrical signal from the SPD is fed simultaneously to the frequency counter and the oscilloscope through an electric power divider. The photon detection efficiency, quantum efficiency (PDE or QE), and dark count rate (DCR) are determined based on the frequency counter readings. The oscilloscope displays a histogram of the number of operations over time that determines the dead time (DT) and the after-pulse probability (AP).
System calibration
The laser source needs to be calibrated at the commencement of operation. The repetition rate of optical pulses, as well as their duration, are recorded using an oscilloscope and a multiphoton detector by connecting the laser optical output to the detector that in turn is connected to the oscilloscope (Fig. 4).
Fig. 5 shows the oscillogram of the laser source’s optical pulse. It can be used to determine that the FWHM parameter is approximately 40 ps. Fig. 6 clearly shows that the repetition rate of laser pulses is 100 kHz. If this rate is known, it is possible to set the required optical power using an attenuator in such a way that all losses in the fiber-optic line are considered and, as a result, the detector receive such optical power that would correspond to the generation of coherent states with the statistics of 0.1 photon/pulse. Dependence of the average optical power on the repetition rate of optical pulses for such generation is shown in Fig. 7. The frequencies of 10 kHz, 100 kHz, 1 MHz, 156.25 MHz and 312.5 MHz are used as the reference points. Selection of the last two frequencies is due to the QRate detector operation at these frequencies.
After calibration, the source of laser pulses is connected directly to the SPD under study. During all further measurements, the frequency is set to 100 kHz and the relevant average power is 4.75 nW at the detector input.
Measurement results
The measurements were taken for all four detectors. The test results for the photodetectors were summarized in the tables, and a typical image of the count stacked column chart is shown in Fig. 8.
To adjust the overall scale and visibility of the entire data series, the first peak on this and all subsequent column charts was reduced by 100 times. The column chart in Fig. 9 clearly demonstrates that the dead time in the detector (in this case, it is the test result of QRATE-SPD-GEN1-FR) is 40 µs.
The time-dependent stacking and presentation of counts were performed both for measuring the dead time duration and for calculating the afterpulse probability. To calculate the afterpulse probability, we took the number of signal photon counts in the zero peak and the number of counts occurred between the first and second pulse peaks. A hundred times the ratio of the number of counts in this range to the number of counts in the zero peak provides an approximate value of the afterpulse probability.
Detector QRATE-SPD-GEN1-FR
There were the following presets and calculation results for the QRATE-SPD-GEN1-FR detector (Table 1).
To calculate the afterpulse probability (AP), an exposure was used for 5 minutes. During this period of time, the system accumulated 23,763 photon counts in the zero peak and 177 counts between the subsequent pulses. In accordance with the formula described above, we have the following:
Detector QRATE-SPD-GEN2-FR
Similar to the parameter calculation algorithm for QRATE-SPD-GEN1-FR, the following data were obtained for QRATE-SPD-GEN2-FR (Table 2).
Detector IDQube-NIR-FR-MMF-LN
To broaden the evaluation of the detectors, information relating to the SPDs made by ID Quantique were obtained for various QEs. The bias voltage values for each quantum efficiency were also obtained (Table 3).
Figure 12 shows changes in the number of dark and signal counts depending on the changes in the quantum efficiency. As expected, the count level is increased proportionally to each other as the quantum efficiency is grown. However, when calculating the actual quantum efficiency and comparing it with the determined values, degradation of the actual QE value was found when approaching the maximum allowable values in the software (Fig. 13).
In relation to the IDQube-NIR-FR-MMF-LN model, the afterpulse probability was calculated using the same method as for the QRATE-SPD-GEN1-FR SPD(Fig. 14). It was confirmed that the afterpulse probability was also heightened as the quantum efficiency value was increased (Table 4).
Detector ID230
As opposed to the detectors studied earlier, the ID230 SPD has a fundamentally different cooling system that provides a much lower temperature for the photosensitive element (Tables 5, 6). This feature leads to the better values of dark counts (Fig. 15) and much lower values of the afterpulse probability (Fig. 16).
Conclusion
Based on the results of the studies, it has been concluded that, under equal operating conditions, the QRATE-SPD-GEN1-FR and QRATE-SPD-GEN2-FR detectors have almost equal specifications in terms of quantum efficiency, however, QRATE-SPD-GEN2-FR has better dark count rates that is undoubtedly a result of the improved production technology of the QRATE-SPD-GEN2-FR detector (Table 7).
The study of Swiss-made detectors made by ID Quantique has showed that the declared parameters include some specifications that do not correspond to the specified rated values. This phenomenon has affected mainly the quantum efficiency of the detectors. There are significant drawdowns at the maximum allowable QE values.
If we compare the Russian-made detectors by QRate with the detectors made by ID Quantique at the same quantum efficiency (about 10–13%), then it is possible to say that the QRate detectors are almost equivalent and interchangeable with the IDQube models. Obviously, they cannot be compared with the ID230 model, since the latter uses a different cooling approach that provides the exceptional detector specifications (Table 8).
Acknowledgement
The engineers from LLS SC express their gratitude to their colleagues from QRate for providing the system for work in their research laboratory, as well as for their assistance in data processing and material preparation.
Authors
S. N. Mosentsov, quantum communications engineer, LLS SC, s.mosencov@lenlasers.ru, Saint-Petersburg, Russia.
ORCID: 0000-0003-2678-9663
A. V. Losev, head of development department, QRate LLC, Moscow, Russia.
ORCID: 0000-0002-6030-2532
I. D. Pavlov, technical director, QRate LLC, Moscow, Russia.
ORCID: 0000-0001-8865-556X
V. V. Zavodilenko, leading engineer, QRate LLC, Moscow, Russia.
ORCID: 0000-0002-3252-2984
A. A. Filyaev, scientific project engineer, QRate LLC, Moscow, Russia.
ORCID: 0000-0001-7319-8001
N. V. Burov, director general, LLS SC, Saint-Petersburg, Russia.
Authors’ contributions
The article is prepared on the basis of work of all team members: S. N. Mosentsov – data collection and analysis, article preparation and layout; A. V. Losev – technical consultation and SPD development; I. D. Pavlov – project manager for the SPD development; V. V. Zavodilenko – SPD development; A. A. Filyaev – data collection and analysis; N. V. Burov – arrangement of work and discussion.
ID Quantique
S. N. Mosentsov 1, A. V. Losev 2, V. V. Zavodilenko 2, A. A. Filyaev 1, I. D. Pavlov 2, N. V. Burov 1
LLS SC, Saint-Petersburg, Russia
QRate LLC, Moscow, Russia
The article is devoted to the comparison of specifications of the single photon detectors manufactured by QRate (Russia) and ID Quantique (Switzerland). Their quantum efficiencies, dark count rates, and afterpulse probabilities have been examined in this work. The test results have showed the interchangeability of detectors and non-compliance of foreign detectors with the declared specifications and demonstrated the potential capacities of domestic development.
Keywords: single photon detector, quantum technologies, ID Quantique, QRate, Russian production
Article received: 21.01.2023
Article accepted: 14.02.2023
Introduction
The Russian company QRate, a developer and supplier of comprehensive hardware and software solutions for information security using the quantum technologies, together with specialists from LLS SC, have tested the own-produced single photon detectors (SPDs) and those made by ID Quantique (Switzerland) in its own research laboratory.
All SPDs were provided with the coherent states with the statistic value of 0.1 photon/pulse. On average, 10 light pulses received by the SPD correspond to one pulse with 1 photon and nine pulses without any photons. The SPDs under study are designed in such a way that, by using the electronic avalanche gain effect, they generate a current pulse at the output when even a single photon is absorbed by the photosensitive detector area.
The objectives of study included a comparative description of domestic SPDs and foreign analogues and examination of the real specifications of foreign SPDs.
Four models of detectors were used in the tests:
two QRate models:
QRATE-SPD-GEN1-FR and QRATE-SPD-GEN2-FR;
two ID Quantique models:
IDQube-NIR-FR-MMF-LN and ID230.
System design
and operation algorithm
The single photon detectors were tested using a special automated measuring set-up, specially designed to measure the SPD operating parameters. The set-up included the following:
synchronization system;
laser pulse source;
beam splitter system (BS);
system of controlled optical attenuators with the adjustable output power;
tested SPD;
frequency counter;
oscilloscope.
The set-up design provides fir an additional optical adapter (OA) for arranging parallel measurements for two SPDs. All components of this system are controlled by the software developed in the LabVIEW environment.
A functional circuit diagram of an automated measuring set-up for the SPD operational parameters is shown in Fig. 1. Thick black links indicate the contact of two devices using the HF coaxial cables, thin ones indicate the optical fibers. Fig. 2 shows the individual units of the automated measuring set-up for the SPD operational parameters.
The laser pulses and strobe electrical signals are generated in the same frequency grid, and the phase shift between them is controlled by a synchronization system. The synchronization system is a field-programmable gate array (FPGA) used as a reference frequency generator for the high-frequency laser driver and SPD. The relative phase between the laser pulses and the sinusoidal strobe SPD pulses can be varied to achieve the highest possible count rate with the unchanged other parameters. The laser source is a laser diode with a central wavelength of 1550.12 nm, mounted on a driver board (Fig. 3) and configured using the console line on a computer.
Optical pulses from the source are sent to the beam splitter input, where they are split into two components with an intensity in the ratio 97/3. The beam splitter is used in order to be able to control the shape, duration and repetition rate of laser pulses in a low-power optical arm by detecting a part of the power incident on a multiphoton detector. At the input of two series-connected controlled attenuators incident light of much lower intensity. Since the power of light transmitted through the first attenuator can be measured, and the second attenuator has a fixed attenuation ratio, then the output power of laser pulses can be controlled and maintained at about 0.1 photon per pulse. Such a signal enters the SPD input.
The output electrical signal from the SPD is fed simultaneously to the frequency counter and the oscilloscope through an electric power divider. The photon detection efficiency, quantum efficiency (PDE or QE), and dark count rate (DCR) are determined based on the frequency counter readings. The oscilloscope displays a histogram of the number of operations over time that determines the dead time (DT) and the after-pulse probability (AP).
System calibration
The laser source needs to be calibrated at the commencement of operation. The repetition rate of optical pulses, as well as their duration, are recorded using an oscilloscope and a multiphoton detector by connecting the laser optical output to the detector that in turn is connected to the oscilloscope (Fig. 4).
Fig. 5 shows the oscillogram of the laser source’s optical pulse. It can be used to determine that the FWHM parameter is approximately 40 ps. Fig. 6 clearly shows that the repetition rate of laser pulses is 100 kHz. If this rate is known, it is possible to set the required optical power using an attenuator in such a way that all losses in the fiber-optic line are considered and, as a result, the detector receive such optical power that would correspond to the generation of coherent states with the statistics of 0.1 photon/pulse. Dependence of the average optical power on the repetition rate of optical pulses for such generation is shown in Fig. 7. The frequencies of 10 kHz, 100 kHz, 1 MHz, 156.25 MHz and 312.5 MHz are used as the reference points. Selection of the last two frequencies is due to the QRate detector operation at these frequencies.
After calibration, the source of laser pulses is connected directly to the SPD under study. During all further measurements, the frequency is set to 100 kHz and the relevant average power is 4.75 nW at the detector input.
Measurement results
The measurements were taken for all four detectors. The test results for the photodetectors were summarized in the tables, and a typical image of the count stacked column chart is shown in Fig. 8.
To adjust the overall scale and visibility of the entire data series, the first peak on this and all subsequent column charts was reduced by 100 times. The column chart in Fig. 9 clearly demonstrates that the dead time in the detector (in this case, it is the test result of QRATE-SPD-GEN1-FR) is 40 µs.
The time-dependent stacking and presentation of counts were performed both for measuring the dead time duration and for calculating the afterpulse probability. To calculate the afterpulse probability, we took the number of signal photon counts in the zero peak and the number of counts occurred between the first and second pulse peaks. A hundred times the ratio of the number of counts in this range to the number of counts in the zero peak provides an approximate value of the afterpulse probability.
Detector QRATE-SPD-GEN1-FR
There were the following presets and calculation results for the QRATE-SPD-GEN1-FR detector (Table 1).
To calculate the afterpulse probability (AP), an exposure was used for 5 minutes. During this period of time, the system accumulated 23,763 photon counts in the zero peak and 177 counts between the subsequent pulses. In accordance with the formula described above, we have the following:
Detector QRATE-SPD-GEN2-FR
Similar to the parameter calculation algorithm for QRATE-SPD-GEN1-FR, the following data were obtained for QRATE-SPD-GEN2-FR (Table 2).
Detector IDQube-NIR-FR-MMF-LN
To broaden the evaluation of the detectors, information relating to the SPDs made by ID Quantique were obtained for various QEs. The bias voltage values for each quantum efficiency were also obtained (Table 3).
Figure 12 shows changes in the number of dark and signal counts depending on the changes in the quantum efficiency. As expected, the count level is increased proportionally to each other as the quantum efficiency is grown. However, when calculating the actual quantum efficiency and comparing it with the determined values, degradation of the actual QE value was found when approaching the maximum allowable values in the software (Fig. 13).
In relation to the IDQube-NIR-FR-MMF-LN model, the afterpulse probability was calculated using the same method as for the QRATE-SPD-GEN1-FR SPD(Fig. 14). It was confirmed that the afterpulse probability was also heightened as the quantum efficiency value was increased (Table 4).
Detector ID230
As opposed to the detectors studied earlier, the ID230 SPD has a fundamentally different cooling system that provides a much lower temperature for the photosensitive element (Tables 5, 6). This feature leads to the better values of dark counts (Fig. 15) and much lower values of the afterpulse probability (Fig. 16).
Conclusion
Based on the results of the studies, it has been concluded that, under equal operating conditions, the QRATE-SPD-GEN1-FR and QRATE-SPD-GEN2-FR detectors have almost equal specifications in terms of quantum efficiency, however, QRATE-SPD-GEN2-FR has better dark count rates that is undoubtedly a result of the improved production technology of the QRATE-SPD-GEN2-FR detector (Table 7).
The study of Swiss-made detectors made by ID Quantique has showed that the declared parameters include some specifications that do not correspond to the specified rated values. This phenomenon has affected mainly the quantum efficiency of the detectors. There are significant drawdowns at the maximum allowable QE values.
If we compare the Russian-made detectors by QRate with the detectors made by ID Quantique at the same quantum efficiency (about 10–13%), then it is possible to say that the QRate detectors are almost equivalent and interchangeable with the IDQube models. Obviously, they cannot be compared with the ID230 model, since the latter uses a different cooling approach that provides the exceptional detector specifications (Table 8).
Acknowledgement
The engineers from LLS SC express their gratitude to their colleagues from QRate for providing the system for work in their research laboratory, as well as for their assistance in data processing and material preparation.
Authors
S. N. Mosentsov, quantum communications engineer, LLS SC, s.mosencov@lenlasers.ru, Saint-Petersburg, Russia.
ORCID: 0000-0003-2678-9663
A. V. Losev, head of development department, QRate LLC, Moscow, Russia.
ORCID: 0000-0002-6030-2532
I. D. Pavlov, technical director, QRate LLC, Moscow, Russia.
ORCID: 0000-0001-8865-556X
V. V. Zavodilenko, leading engineer, QRate LLC, Moscow, Russia.
ORCID: 0000-0002-3252-2984
A. A. Filyaev, scientific project engineer, QRate LLC, Moscow, Russia.
ORCID: 0000-0001-7319-8001
N. V. Burov, director general, LLS SC, Saint-Petersburg, Russia.
Authors’ contributions
The article is prepared on the basis of work of all team members: S. N. Mosentsov – data collection and analysis, article preparation and layout; A. V. Losev – technical consultation and SPD development; I. D. Pavlov – project manager for the SPD development; V. V. Zavodilenko – SPD development; A. A. Filyaev – data collection and analysis; N. V. Burov – arrangement of work and discussion.
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