All-optical phase-sensitive detection for ultra-fast quantum computation

Takanashi, Naoto; Inoue, Asuka; Kashiwazaki, Takahiro; Kazama, Takushi; Enbutsu, Koji; Kasahara, Ryoichi; Umeki, Takeshi; Furusawa, Akira

doi:10.1364/oe.405832

Cited by 49 publications

(23 citation statements)

References 42 publications

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“…A completely different approach to overcome this limitation is to use high-gain OPAs for quadrature measurement, as shown in Fig. 9 [125,130,131]. The parametric amplification process selects one of the quadratures of an optical field and amplifies it without adding noise while attenuating the other quadrature.…”

Section: Ultra-broadband Quadrature Measurementmentioning

confidence: 99%

“…In 2019, an over-30-dBgain OPA was reported by a highly durable PPLN waveguide with a continuous pump beam [134]. In 2020, the PPLN waveguides were used both for squeezed light generation and quadrature measurement [125]. As a result, 3-dB squeezing was observed over 3 THz by detecting the amplified optical signal with an optical spectrum analyzer.…”

Section: Ultra-broadband Quadrature Measurementmentioning

confidence: 99%

“…squeezed light sources and measurement based on waveguide OPAs [117,124,125] will be an enabler for ultra-broadband all-optical quantum teleportation circuits. Such all-optical teleportation circuits can be further extended to more advanced QC protocols, such as one-way QC and measurementinduced gate operations, opening the path for the all-optical QC with over-THz bandwidth.…”

Section: Towards Ultra-broadband Qc By All-optical Meansmentioning

confidence: 99%

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Building a large-scale quantum computer with continuous-variable optical technologies

Fukui,

Takeda

2021

Preprint

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Realizing a large-scale quantum computer requires hardware platforms that can simultaneously achieve universality, scalability, and fault tolerance. As a viable pathway to meeting these requirements, quantum computation based on continuous-variable optical systems has recently gained more attention due to its unique advantages and approaches. This review introduces several topics of recent experimental and theoretical progress in the optical continuous-variable quantum computation that we believe are promising. In particular, we focus on scaling-up technologies enabled by time multiplexing, bandwidth broadening, and integrated optics, as well as hardware-efficient and robust bosonic quantum error correction schemes.

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Section: Ultra-broadband Quadrature Measurementmentioning

confidence: 99%

Section: Ultra-broadband Quadrature Measurementmentioning

confidence: 99%

Section: Towards Ultra-broadband Qc By All-optical Meansmentioning

confidence: 99%

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Building a large-scale quantum computer with continuous-variable optical technologies

Fukui,

Takeda

2021

Preprint

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“…virtual array concept as widely adopted in millimeter-wave (mmWave) channel sounding campaigns [11]. Besides, many sub-THz applications e.g., phasesensitive detection, requires the system to be highly phase stable [12]. However, the phase of the current sub-THz channel sounder is often unstable.…”

Section: Introductionmentioning

confidence: 99%

Design and Validation of the Phase-Compensated Long-Range Sub-THz VNA-Based Channel Sounder

Lyu

Mbugua

Olesen

et al. 2021

Antennas Wirel. Propag. Lett.

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This paper presents the first vector network analyzer (VNA)-based sub-Terahertz (sub-THz) phase-compensated channel sounder at 220-330 GHz using radio-over-fiber (RoF) techniques that could enable long-range phase-coherent measurements. The optical cable solution enables long-range channel measurements at sub-THz bands, since it can effectively minimize the cable loss. This paper also proposes a novel phase compensation scheme to stabilize the phase variations introduced by optical fiber of the channel sounder to enable its application in multichannel/antenna measurements. This proposed channel sounder is validated in back-to-back measurements under two optical cable conditions, i.e., with presence of thermal changes and mechanical stress. The phase variation introduced by the cable effects in the system is shown to be over 400 • in 220-330 GHz, compared to 15 • at 220-288 GHz and 37 • in 288-330 GHz after compensation, respectively, demonstrating the robustness and effectiveness of the developed channel sounder in practice. The developed system, which has a dynamic range of 106.7 dB, can support measurement range up to 300 m (limited by the optical cable length in our system and subject to over-the-air signal transmission loss in practical environment).

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“…As of today, we are far from this limit. Assuming realizations with recent experimental demonstrations of large detection and squeezing bandwidths [35,36] in the tera-hertz regime, and assuming comparable experimental control (though this may be challenging), temporal encoded computation schemes can potentially perform computation on information encoded in millions of modes.…”

Section: Introductionmentioning

confidence: 99%

Continuous Variable Cluster State Computation

Larsen

Neergaard-Nielsen

Andersen

2021

Conference on Lasers and Electro-Optics

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In measurement-based quantum computation (MBQC), or cluster state computation, gates are implemented on a multi-mode entangled cluster state by projective measurements. In the optical continuous variable (CV) regime, such cluster state can be deterministically generated while a class of measurements is efficiently implemented by homodyne detection. This immediately allows for the deterministic implementation of Gaussian gates in a scalable optical computation platform.In this thesis, work towards the realization of CV MBQC is presented. In MBQC, a cluster state of at least two dimensions is required, and in this thesis, the generation of such two-dimensional (2D) cluster state is proposed and experimentally demonstrated. Assuming the availability of Gottesman-Kitaev-Preskill (GKP) encoded input qubits, a universal computation scheme for the 2D cluster state is proposed, and noise analysis of the computation scheme is carried out and compared to other computation schemes on 2D cluster states. Following the proposed computation scheme, a universal Gaussian gate set is implemented on the generated cluster state by projective measurements, and to demonstrate the programmability, gates are combined into a small quantum circuit. Gate noise, caused by finite squeezing, is characterized, and the requirements for faulttolerant computation are discussed. Finally, a new computation scheme is proposed where gates are implemented on a three-dimensional cluster state allowing topological error correction. Taking finite squeezing in both the cluster state generation and approximate GKP-states into account, fault-tolerant computation is shown to be possible by simulation when the squeezing level is above a certain squeezing threshold.To aid the experimental implementations, the focus throughout this thesis is on temporal encoding where resources are reused in time minimizing the required spatial resources, i.e. time multiplexing. To this end, the thesis starts with a demonstration of two-mode squeezed state generation in two spatial modes from a single time-multiplexed squeezed light source using optical switching and delay. In this demonstration, multiple experimental techniques are developed, including efficient free-space to fiber coupling, in-fiber phase control, and fiber-based homodyne detection, each of which plays important roles in the experimental demonstration of the following cluster state generation and gate implementation.iii group at DTU Physics, supported by the Danish National Research Foundation, and was supervised by group leader professor Ulrik L. Andersen and senior researcher Jonas S. Neergaard-Nielsen. I joined the group for my master project, and in 2017, Ulrik gave me the opportunity to continue my work as a PhD student for which I am greatly thankful. QPIT is a diverse group of many research topics within quantum mechanics, driven by a large and diverse group of people representing every corner of the world. It has been inspiring and great fun working in the QPIT group for the last 4 years. Here you can...

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All-optical phase-sensitive detection for ultra-fast quantum computation

Cited by 49 publications

References 42 publications

Building a large-scale quantum computer with continuous-variable optical technologies

Building a large-scale quantum computer with continuous-variable optical technologies

Design and Validation of the Phase-Compensated Long-Range Sub-THz VNA-Based Channel Sounder

Continuous Variable Cluster State Computation

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