Experimental Quantum Key Distribution with Integrated Silicon Photonics and Electronics

Editors' Suggestion

Experimental Quantum Key Distribution with Integrated Silicon Photonics and Electronics

Chen-Xi Zhu, Zhao-Yuan Chen, Yang Li, Xin-Zhe Wang, Chao-Ze Wang, Yu-Long Zhu, Fu-Tian Liang, Wen-Qi Cai, Ge Jin, Sheng-Kai Liao, and Cheng-Zhi Peng

Phys. Rev. Applied 17, 064034 – Published 16 June 2022

Abstract

Quantum key distribution (QKD) provides a methodology for secure key distribution based on fundamental physical laws. Although significant experimental progress has been made, the previous QKD systems are mainly composed of discrete optical and electronic devices. Here, we present a prototype of a QKD transmitter by developing the technologies of integrated silicon photonics and electronics. The photonic chip integrates the essential encoding components for the decoy-state BB84 protocol using polarization encoding, while the electronic chips integrate the dedicated driving circuits. On the basis of these integrated chips, we build a desktop QKD system to verify their performance. Successful QKD experiments are conducted at a repetition frequency of 312.5 MHz using standard fiber and emulated channel loss and the intrinsic quantum bit error rate of the system is as low as 0.41%. The finite-key secret rate is 42.7 kbit/s for the 100-km fiber and 295.5 bit/s for the 40-dB emulated loss. Our results demonstrate the feasibility of QKD based on integrated optoelectronic devices and hopefully take a fundamental toward a system-in-a-package solution.

Received 5 January 2022
Accepted 12 May 2022

DOI:https://doi.org/10.1103/PhysRevApplied.17.064034

Physics Subject Headings (PhySH)

Integrated optics Optical quantum information processing Optoelectronics Quantum communication Quantum cryptography

Devices

Quantum Information, Science & TechnologyAtomic, Molecular & Optical

Authors & Affiliations

Chen-Xi Zhu ¹, Zhao-Yuan Chen^2,3,4,5, Yang Li ^2,3,4,*, Xin-Zhe Wang ^2,3,4,†, Chao-Ze Wang^1,2,3,4, Yu-Long Zhu ⁶, Fu-Tian Liang^2,3,4, Wen-Qi Cai^2,3,4, Ge Jin⁶, Sheng-Kai Liao ^1,2,3,4,‡, and Cheng-Zhi Peng^2,3,4

¹School of Cyberspace Security, University of Science and Technology of China, Hefei 230026, China
²Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
³Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
⁴Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
⁵PLA Rocket Force University of Engineering, Xi’an 710025, China
⁶Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China

^*liyang9@ustc.edu.cn
^†wxzyf@ustc.edu.cn
^‡skliao@ustc.edu.cn

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 17, Iss. 6 — June 2022

Subject Areas

Reuse & Permissions

Access Options

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
The structural illustration of the integrated photonic chip and the two integrated electronic chips. (a) A schematic of the photonics integrated chip. All essential encoding components are integrated within a footprint of $3 \times 4.8 {mm}^{2}$ , including a grating coupler (GC) and a two-dimensional grating coupler (2DGC) for the optical input and output, a thermo-optic modulator (TOM) and a carrier-depletion modulator (CDM) as the intensity modulator (IM) and polarization modulator (PM), and a monitor photon detector (MPD) as the optical power monitor. (b) A schematic of the laser driver chip (LDC), which is integrated within a footprint of $1.93 \times 1.2 {mm}^{2}$ . (c) A schematic of the modulator driver chip (MDC), which is integrated within a footprint of $1.44 \times 1.03 {mm}^{2}$ . VCDL, voltage control delay link; SPI, serial peripheral interface; and, and gate; SDC, single-ended differential conversion; LA, limiting amplifier; OD, open drain; BGR, band-gap reference; FB, feedback.
Reuse & Permissions
Figure 2
(a) The experimental setup of the chip-based QKD. (b)–(d) Microscope images of the PIC, LDC, and MDC chip, respectively. LD, laser diode; FP, Fabry-Perot filter; FPGA, field-programmable gate array; ATT, attenuator; BS, beam splitter; PC, polarization controller; PBS, polarizing beam splitter; SPD, single-photon detector.
Reuse & Permissions
Figure 3
(a) The measured results of the MPD current (blue dots) and the output optical power (orange squares) when scanning the applied continuous dc voltage of the PIC IM. (b) The four prepared polarization states for the BB84 protocol on the Poincaré sphere. (c) The measured short optical pulses using a 12-GHz-bandwidth photoreceiver. (d) The amplified MDC output signals, which have four independent random amplitudes. The data in (c) and (d) are acquired by a 16-GHz-bandwidth oscilloscope and the color bar represents the normalized frequency of occurrence.
Reuse & Permissions
Figure 4
(a) The measured polarization error rate under random modulation. The channel is emulated using a 28-dB VOA and the measured polarization error rate is approximately $0.41 % \pm 0.06 %$ within 3 h. All data are collected without any active adjustment of the chip-based QKD system. (b),(c) The extracted quantum bit error rate (QBER) and secure key rate (SKR) with the emulated channels using either a fiber pool or a VOA and with the two types of SNSPDs and $(In, Ga) As$ APDs. The blue and red lines represent the theoretically calculated SKR and QBER with the SNSPD and the $(In, Ga) As$ SPD, respectively. The solid circles and squares are measurement results of emulated losses using the VOA with quantum photon synchronization, while the hollow circles and squares are measurement results with local synchronization. The asterisks are the measurement results for the 100-km and 150-km fiber spools, respectively.
Reuse & Permissions

Physical Review Applied