Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Conference on Lasers and Electro-Optics Pacific Rim (CLEO-PR)

Ultrafast Measurement of Femtosecond Time-bin Qubits Using Optimized Up-conversion Single Photon Detector

Yuta Kochi, Sunao Kurimura, Junko Ishi‐Hayase

Published Jul 31, 2022• 0 citations
Publisher

Abstract

We developed and optimized the up-conversion single photon detector with the temporal resolution of 415 fs. Consequently, we successfully evaluated single-photon level pseudo time-bin qubits with their pulse interval of only 800 fs.
DOI
10.1109/cleo-pr62338.2022.10432227

Related papers

Ultrafast Measurement of Femtosecond Time-bin Qubits Using Optimized Up-conversion Single Photon Detector

Yuta Kochi, Sunao Kurimura, Junko Ishi‐Hayase

We developed and optimized the up-conversion single photon detector with the temporal resolution of 415 fs. Consequently, we successfully evaluated single-photon level pseudo time-bin qubits with their pulse interval of only 800 fs.

Conference on Lasers and Electro-Optics Pacific Rim (CLEO-PR)•Jan 1, 2022•0 citations

Evaluation of Femtosecond Time-bin Qubits Using Frequency Up-conversion Technique

Yuta Kochi, Sunao Kurimura, Junko Ishi‐Hayase

Time-bin qubits, in which quantum information is encoded in a single photon at different times $Δ$t, are suitable for long-distance transmission via optical fibers. However, detection of time-bin qubits has been limited to the nanosecond range owing to the limited temporal resolution of single-photon detectors. In this study, we developed an up-conversion single-photon detector (UCSPD), using commercial nonlinear crystals of different lengths. By changing the crystal length and pump power, we quantitatively evaluated the efficiency and temporal resolution of the UCSPD and determined the optimal conditions for measuring femtosecond time-bin qubits. This detector achieved a temporal resolution of 415 fs and up-conversion efficiency of 10.1 %. Consequently, we successfully evaluated single-photon level pseudo femtosecond time-bin qubits with a pulse interval of only 800 fs.

arXiv:2205.06957•May 14, 2022•2 citations

Optimization of crystal length in a pulse-pumped up-conversion single-photon detector for decoding femtosecond time-bin qubits

Yuta Kochi, Sunao Kurimura, Junko Ishi‐Hayase

In advancing ultrafast quantum communication and computing, it is crucial to develop precise time-resolved measurement techniques for single-photon pulses. However, the measurement of photonic qubits, especially time-bin qubits, is limited by the temporal resolution of single-photon detectors, typically around tens of picoseconds. In this study, we developed a pulse-pumped up-conversion single-photon detector (UCSPD) using periodically poled Mg-doped stoichiometric lithium tantalate (PPMg:SLT) crystals of varying lengths to optimize femtosecond up-conversion. We evaluated the UCSPD’s efficiency and temporal resolution using a convolution model that accounts for group delay in nonlinear crystals. Our results demonstrate that the model calculations enable the accurate prediction of the crystal length dependence of temporal resolution and up-conversion efficiency without fitting parameters. The UCSPD achieved 415 fs resolution and 10.1 \% efficiency with a 2 mm crystal, enabling successful characterization of time-bin qubits with 800 fs pulse intervals.

Optics Express•Dec 1, 2024•1 citation

Evaluation of Femtosecond Time-bin Photon Echo from Quantum Dot Ensemble using Frequency Up-conversion Technique

Yuta Kochi, Yutaro Kinoshita, Sunao Kurimura +2 more

We have succeeded in femtosecond time-bin pulses storage/retrieval by a photon echo method with a quantum dot ensemble. Moreover, we have developed an up-conversion single-photon detector and evaluated the ultraweak femtosecond time-bin echo signal.

•Jan 1, 2023•2 citations

Ultrafast coherent measurement of time-bin qubits using chirped-pulse upconversion

John M. Donohue, Megan Agnew, Jonathan Lavoie +1 more

Using shaped pulses and nonlinear optics, we have experimentally demonstrated coherent measurement of time-bin encoded photons with temporal separations two orders of magnitude smaller than detector resolution by converting timing information to frequency.

The Rochester Conferences on Coherence and Quantum Optics and the Quantum Information and Measurement meeting•Jan 1, 2013•0 citations

Femtosecond Regime Photon Echo with Quantum Dots Evaluated by Up-conversion Single-photon Detector

Yuta Kochi, Sunao Kurimura, Kouichi Akahane +1 more

Recently, quantum information processing and communications using photons have been attracting attention. To increase the density of transmitted photonic qubits, it is necessary to develop broadband quantum memories and detectors that can handle ultrashort pulses. Although rare-earth-ion doped quantum memories [1] have been widely studied, due to their storage bandwidth of ~GHz, they are incapable of storing ultrashort pulses. In our group, we used the photon echo (PE) method with quantum dots (QDs) to realize ultra-short femtosecond pulse storage. However, we encountered many difficulties in realizing this method such as low PE efficiency from the QDs and the insufficient temporal resolution of the avalanche single-photon detectors. To solve these problems, we have applied a new quantum control method and utilized an up-conversion single-photon detector (UCSPD) [2]. In this presentation, we will introduce the techniques “1. Time-resolving measurement by UCSPD,” “2. PE quantum memory using QDs” and “3. enhancement of PE signals.”

JSAP-OSA Joint Symposia•Jan 1, 2024•0 citations
Time-bin qubits, in which quantum information is encoded in a single photon at different times ΔΔΔt, are suitable for long-distance transmission via optical fibers. However, detection of time-bin qubits has been limited to the nanosecond range owing to the limited temporal resolution of single-photon detectors. In this study, we developed an up-conversion single-photon detector (UCSPD), using commercial nonlinear crystals of different lengths. By changing the crystal length and pump power, we quantitatively evaluated the efficiency and temporal resolution of the UCSPD and determined the optimal conditions for measuring femtosecond time-bin qubits. This detector achieved a temporal resolution of 415 fs and up-conversion efficiency of 10.1 %. Consequently, we successfully evaluated single-photon level pseudo femtosecond time-bin qubits with a pulse interval of only 800 fs.
In advancing ultrafast quantum communication and computing, it is crucial to develop precise time-resolved measurement techniques for single-photon pulses. However, the measurement of photonic qubits, especially time-bin qubits, is limited by the temporal resolution of single-photon detectors, typically around tens of picoseconds. In this study, we developed a pulse-pumped up-conversion single-photon detector (UCSPD) using periodically poled Mg-doped stoichiometric lithium tantalate (PPMg:SLT) crystals of varying lengths to optimize femtosecond up-conversion. We evaluated the UCSPD’s efficiency and temporal resolution using a convolution model that accounts for group delay in nonlinear crystals. Our results demonstrate that the model calculations enable the accurate prediction of the crystal length dependence of temporal resolution and up-conversion efficiency without fitting parameters. The UCSPD achieved 415 fs resolution and 10.1 \% efficiency with a 2 mm crystal, enabling successful characterization of time-bin qubits with 800 fs pulse intervals.
Recently, quantum information processing and communications using photons have been attracting attention. To increase the density of transmitted photonic qubits, it is necessary to develop broadband quantum memories and detectors that can handle ultrashort pulses. Although rare-earth-ion doped quantum memories [1] have been widely studied, due to their storage bandwidth of ~GHz, they are incapable of storing ultrashort pulses. In our group, we used the photon echo (PE) method with quantum dots (QDs) to realize ultra-short femtosecond pulse storage. However, we encountered many difficulties in realizing this method such as low PE efficiency from the QDs and the insufficient temporal resolution of the avalanche single-photon detectors. To solve these problems, we have applied a new quantum control method and utilized an up-conversion single-photon detector (UCSPD) [2]. In this presentation, we will introduce the techniques “1. Time-resolving measurement by UCSPD,” “2. PE quantum memory using QDs” and “3. enhancement of PE signals.”