• Special Issue
  • Quantum Photonics
  • 9 Article (s)
Quantum photonics: feature introduction
Xian-Min Jin, M. S. Kim, and Brian J. Smith
Photonics Research
  • Publication Date: Dec. 01, 2019
  • Vol.7 Issue, 12 12000QP1 (2019)
Low-noise InGaAs/InP single-photon detector with widely tunable repetition rates
Yan Liang, Qilai Fei, Zhihe Liu, Kun Huang, and Heping Zeng
InGaAs/InP avalanche photodiodes typically work in the gated Geiger mode to achieve near-infrared single-photon detection. By using ultrashort gates and combining with the robust spike-canceling technique that consists of the capacitance-balancing and low-pass filtering technique, we demonstrate an InGaAs/InP single-photon detector (SPD) with widely tunable repetition rates in this paper. The operation frequency could be tuned conveniently from 100 MHz to 1.25 GHz with the SPD’s performance measured to maintain good performance, making it quite suitable for quantum key distribution, laser ranging, and optical time domain reflectometry. Furthermore, the SPD exhibited extremely low-noise characteristics. The detection efficiency of this SPD could reach 20% with the dark count rate of 2.5×10 6/gate and after-pulse probability of 4.1% at 1 GHz.
Photonics Research
  • Publication Date: Feb. 08, 2019
  • Vol.7 Issue, 3 030000A1 (2019)
Limitations of teleporting a qubit via a two-mode squeezed state
Seok Hyung Lie, and Hyunseok Jeong
Recently, a teleportation scheme using a two-mode squeezed state to teleport a photonic qubit, so called a “hybrid” approach, has been suggested and experimentally demonstrated as a candidate to overcome the limitations of all-optical quantum information processing. We find, however, that there exists the upper bound of fidelity when teleporting a photonic qubit via a two-mode squeezed channel under a lossy environment. The increase of photon loss decreases this bound, and teleportation better than this limit is impossible even when the squeezing degree of the teleportation channel becomes infinity. Our result indicates that the hybrid scheme can be valid for fault-tolerant quantum computing only when the photon loss rate can be suppressed under a certain limit.
Photonics Research
  • Publication Date: Apr. 15, 2019
  • Vol.7 Issue, 5 050000A7 (2019)
Sensing and tracking enhanced by quantum squeezing
Chuan Xu, Lidan Zhang, Songtao Huang, Taxue Ma, Fang Liu, Hidehiro Yonezawa, Yong Zhang, and Min Xiao
Quantum sensing, along with quantum communications and quantum computing, is commonly considered as the most important application of quantum optics. Among the quantum-sensing experiments, schemes based on squeezed states of light are popular choices due to their natural quadrature components. Since the first experimental demonstration of quantum-squeezing-enhanced phase measurement beyond the shot-noise limit in 1987, quantum-squeezing techniques toward practical sensing and tracking have been extensively investigated. In this paper, we briefly review the recent developments of quantum squeezing and its applications in several advanced systems for measurements of position, rotation, dynamic motion, magnetic fields, and gravitational waves. We also introduce the recent experimental efforts to combine the quantum-squeezing lights into fiber sensing systems.
Photonics Research
  • Publication Date: May. 03, 2019
  • Vol.7 Issue, 6 06000A14 (2019)
High-dimension experimental tomography of a path-encoded photon quantum state
D. Curic, L. Giner, and J. S. Lundeen
Quantum information protocols often rely on tomographic techniques to determine the state of the system. A popular method of encoding information is on the different paths a photon may take, e.g., parallel waveguides in integrated optics. However, reconstruction of states encoded onto a large number of paths is often prohibitively resource intensive and requires complicated experimental setups. Addressing this, we present a simple method for determining the state of a photon in a superposition of d paths using a rotating one-dimensional optical Fourier transform. We establish the theory and experimentally demonstrate the technique by measuring a wide variety of six-dimensional density matrices. The average fidelity of these with the expected state is as high as 0.9852±0.0008. This performance is comparable to or exceeds established tomographic methods for other types of systems.
Photonics Research
  • Publication Date: Jun. 05, 2019
  • Vol.7 Issue, 7 07000A27 (2019)
Chip-based squeezing at a telecom wavelength
F. Mondain, T. Lunghi, A. Zavatta, E. Gouzien, F. Doutre, M. De Micheli, S. Tanzilli, and V. D’Auria
We demonstrate a squeezing experiment exploiting the association of integrated optics and telecom technology as key features for compact, stable, and practical continuous variable quantum optics. In our setup, squeezed light is generated by single-pass spontaneous parametric down conversion on a lithium niobate photonic circuit and detected by a homodyne detector whose interferometric part is directly integrated on the same platform. The remaining parts of the experiment are implemented using commercial plug-and-play devices based on guided-wave technologies. We measure, for a CW pump power of 40 mW, a squeezing level of 2.00±0.05 dB(anti-squeezing 2.80±0.05 dB), thus confirming the validity of our approach and opening the way toward miniaturized and easy-to-handle continuous variable-based quantum systems.
Photonics Research
  • Publication Date: Jun. 07, 2019
  • Vol.7 Issue, 7 07000A36 (2019)
Transmission of photonic polarization states through 55-m water: towards air-to-sea quantum communication
Cheng-Qiu Hu, Zeng-Quan Yan, Jun Gao, Zhi-Qiang Jiao, Zhan-Ming Li, Wei-Guan Shen, Yuan Chen, Ruo-Jing Ren, Lu-Feng Qiao, Ai-Lin Yang, Hao Tang, and Xian-Min Jin
Quantum communication has been rapidly developed due to its unconditional security and successfully implemented through optical fibers and free-space air in experiments. To build a complete quantum communication network involving satellites in space and submersibles in ocean, the underwater quantum channel has been investigated in both theory and experiment. However, the question of whether the polarization encoded qubit can survive through a long-distance and high-loss underwater channel, which is considered as the restricted area for satellite-borne radio waves, still remains. Here, we experimentally demonstrate the transmission of blue-green photonic polarization states through 55-m-long water. We prepare six universal quantum states at the single photon level and observe their faithful transmission in a large marine test platform. We obtain complete information of the channel by quantum process tomography. The distance demonstrated in this work reaches a region allowing potential real applications, representing a step further towards air-to-sea quantum communication.
Photonics Research
  • Publication Date: Jul. 25, 2019
  • Vol.7 Issue, 8 08000A40 (2019)
Generation of optical Fock and W states with single-atom-based bright quantum scissors
Ziv Aqua, M. S. Kim, and Barak Dayan
We introduce a multi-step protocol for optical quantum state engineering that performs as “bright quantum scissors,” namely truncates an arbitrary input quantum state to have at least a certain number of photons. The protocol exploits single-photon pulses and is based on the effect of single-photon Raman interaction, which is implemented with a single three-level Λ system (e.g., a single atom) Purcell-enhanced by a single-sided cavity. A single step of the protocol realizes the inverse of the bosonic annihilation operator. Multiple iterations of the protocol can be used to deterministically generate a chain of single photons in a W state. Alternatively, upon appropriate heralding, the protocol can be used to generate Fock-state optical pulses. This protocol could serve as a useful and versatile building block for the generation of advanced optical quantum states that are vital for quantum communication, distributed quantum information processing, and all-optical quantum computing.
Photonics Research
  • Publication Date: Oct. 23, 2019
  • Vol.7 Issue, 11 11000A45 (2019)
Experimental test of error-disturbance uncertainty relation with continuous variables
Yang Liu, Haijun Kang, Dongmei Han, Xiaolong Su, and Kunchi Peng
Photonics Research
  • Publication Date: Oct. 31, 2019
  • Vol.7 Issue, 11 11000A56 (2019)

Quantum photonics is an increasingly important emerging field because of the rising demand for experimental demonstration of quantum communication, quantum computing, and quantum simulation, and photonic chips possess prominent advantages as a potential analog for digital quantum computers and a versatile tool for probing fundamental quantum physics.

Using the photonic structure to form a large state-space not only may be fundamentally interesting but also may provide a powerful platform for quantum simulation and quantum computing. This Feature Issue will explore the use of photonic platforms to investigate quantum advantage/supremacy in various quantum computing protocols, such as Boson sampling, quantum walk, fast hitting, and even universal quantum computing protocols.