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

Two-Step Frequency Conversion for Connecting Distant Quantum Memories

Shuhei Tamura, Kohei Ikeda, Kotaro Okamura, Kazumichi Yoshii, Feng-Lei Hong, Tomoyuki Horikiri, Hideo Kosaka

Published Jan 1, 2018• 0 citations
Publisher

Abstract

We demonstrate a two-step frequency conversion process (from 637.2 nm to the telecommunication wavelength and back). Signal-to-noise ratio is estimated to be sufficient for connecting nitrogen-vacancy centers in diamond based quantum repeater.
DOI
10.1364/cleopr.2018.w2g.3

Related papers

Two-step frequency conversion for connecting distant quantum memories by transmission through an optical fiber

Shuhei Tamura, Kohei Ikeda, Kotaro Okamura +4 more

Abstract Long-distance quantum communication requires entanglement between distant quantum memories. For this purpose, photon transmission is necessary to connect the distant memories. Here, for the first time, we develop a two-step frequency conversion process (from a visible wavelength to a telecommunication wavelength and back) involving the use of independent two-frequency conversion media where the target quantum memories are nitrogen-vacancy centers in diamonds (with an emission/absorption wavelength of 637.2 nm), and experimentally characterize the performance of this process acting on light from an attenuated CW laser. A total conversion efficiency of approximately 7% is achieved. The noise generated in the frequency conversion processes is measured, and the signal-to-noise ratio is estimated for a single photon signal emitted by a nitrogen-vacancy (NV) center. The developed frequency conversion system has future applications via transmission through a long optical fiber channel at a telecommunication wavelength for a quantum repeater network.

arXiv:1805.00174•Japanese Journal of Applied Physics•Apr 26, 2018•13 citations

Two-step frequency conversion for connecting distant quantum memories by transmission through an optical fiber

Shuhei Tamura, Kohei Ikeda, Kotaro Okamura +1 more

Long-distance quantum communication requires entanglement between distant quantum memories. For this purpose, photon transmission is necessary to connect the distant memories. Here, for the first time, we develop a two-step frequency conversion process (from a visible wavelength to a telecommunication wavelength and back) involving the use of independent two-frequency conversion media where the target quantum memories are nitrogen-vacancy centers in diamonds (with an emission/absorption wavelength of 637.2 nm), and experimentally characterize the performance of this process acting on light from an attenuated CW laser. A total conversion efficiency of approximately 7% is achieved. The noise generated in the frequency conversion processes is measured, and the signal-to-noise ratio is estimated for a single photon signal emitted by a nitrogen-vacancy (NV) center. The developed frequency conversion system has future applications via transmission through a long optical fiber channel at a telecommunication wavelength for a quantum repeater network.

•Apr 26, 2018•11 citations

Quantum frequency conversion of quantum memory compatible photons to telecommunication wavelengths

Xavier Fernandez-Gonzalvo, Giacomo Corrielli, Boris Albrecht +3 more

We report an experiment demonstrating quantum frequency conversion of weak light pulses compatible with atomic quantum memories to telecommunication wavelengths. We use a PPLN nonlinear waveguide to convert weak coherent states at the single photon level with a duration of 30 ns from a wavelength of 780 nm to 1552 nm. We measure a maximal waveguide internal (external) conversion efficiency η(int) = 0.41 (η(ext) = 0.25), and we show that the signal to noise ratio (SNR) is good enough to reduce the input photon number below 1. In addition, we show that the noise generated by the pump beam in the crystal is proportional to the spectral bandwidth of the device, suggesting that narrower filtering could significantly increase the SNR. Finally, we demonstrate that the quantum frequency converter can operate in the quantum regime by converting a time-bin qubit and measuring the qubit fidelity after conversion.

arXiv:1308.0912•Optics Express•Aug 12, 2013•52 citations

Frequency down-conversion for efficient, low-noise quantum frequency converters

Jan Fabian Geus, Florian Elsen, Sebastian Nyga +3 more

We present a novel device for the efficient, low-noise down-conversion of low-power light from the red visible spectrum. It can be applied to interface electronic spin-qubits in nitrogen-vacancy centers in diamond to the telecommunication wavelengths and thus offers the possibility to implement large-scale quantum networks in existing fiber infrastructure. In comparison to state-of-the-art frequency converters for this application, the device presented here generates an overall noise rate, which is one order of magnitude better than current record values. Simultaneously, an internal conversion efficiency of 50 % was measured. Furthermore, the converter serves as a feasibility demonstration of a general concept for the down-conversion of light from the sub-micron spectral range to telecommunication wavelengths.

Quantum Computing, Communication, and Simulation•Mar 2, 2022•1 citation

Low-noise cascaded frequency conversion of 637.2 nm light to the telecommunication C-band in a single-waveguide device

Fabrice von Chamier, Joscha Hanel, Chris Müller +3 more

Interconnected quantum devices are the building blocks of quantum networks, where state transduction plays a central role. The frequency conversion of photons into the telecommunication C-band is decisive in taking advantage of current low-loss transmission lines. Here, we report the difference frequency conversion of 637.2 nm fluorescent light from a cluster of NV centers in diamond to tunable wavelengths between 1559.0 nm and 1564.9 nm. In order to avoid detrimental noise from spontaneous emissions, we use a two-step conversion device based on a single-pumped periodically poled lithium niobate waveguide. We observed a total external (internal) conversion efficiency of 3.0 ± 0.1 (20.5 ± 0.8) % with a noise rate of 2.4 ± 0.8 (16 ± 5) cps/GHz.

arXiv:2502.14557•Optics Express•Apr 15, 2025•4 citations

Frequency-Stabilized Pump Laser for Wavelength Conversion in Long-Distance Quantum Communication

Kohei Ikeda, Yusuke Hisai, Tomoyuki Horikiri +3 more

We develop a compact frequency-stabilized laser at 1064 nm for wavelength conversion in long-distance quantum communication. Linewidth and frequency stability are demonstrated to be sufficient to connect nitrogen-vacancy centers in diamond in remote nodes.

The Japan Society of Applied Physics•Jan 1, 2018•0 citations
Abstract Long-distance quantum communication requires entanglement between distant quantum memories. For this purpose, photon transmission is necessary to connect the distant memories. Here, for the first time, we develop a two-step frequency conversion process (from a visible wavelength to a telecommunication wavelength and back) involving the use of independent two-frequency conversion media where the target quantum memories are nitrogen-vacancy centers in diamonds (with an emission/absorption wavelength of 637.2 nm), and experimentally characterize the performance of this process acting on light from an attenuated CW laser. A total conversion efficiency of approximately 7% is achieved. The noise generated in the frequency conversion processes is measured, and the signal-to-noise ratio is estimated for a single photon signal emitted by a nitrogen-vacancy (NV) center. The developed frequency conversion system has future applications via transmission through a long optical fiber channel at a telecommunication wavelength for a quantum repeater network.
Long-distance quantum communication requires entanglement between distant quantum memories. For this purpose, photon transmission is necessary to connect the distant memories. Here, for the first time, we develop a two-step frequency conversion process (from a visible wavelength to a telecommunication wavelength and back) involving the use of independent two-frequency conversion media where the target quantum memories are nitrogen-vacancy centers in diamonds (with an emission/absorption wavelength of 637.2 nm), and experimentally characterize the performance of this process acting on light from an attenuated CW laser. A total conversion efficiency of approximately 7% is achieved. The noise generated in the frequency conversion processes is measured, and the signal-to-noise ratio is estimated for a single photon signal emitted by a nitrogen-vacancy (NV) center. The developed frequency conversion system has future applications via transmission through a long optical fiber channel at a telecommunication wavelength for a quantum repeater network.
We report an experiment demonstrating quantum frequency conversion of weak light pulses compatible with atomic quantum memories to telecommunication wavelengths. We use a PPLN nonlinear waveguide to convert weak coherent states at the single photon level with a duration of 30 ns from a wavelength of 780 nm to 1552 nm. We measure a maximal waveguide internal (external) conversion efficiency η(int) = 0.41 (η(ext) = 0.25), and we show that the signal to noise ratio (SNR) is good enough to reduce the input photon number below 1. In addition, we show that the noise generated by the pump beam in the crystal is proportional to the spectral bandwidth of the device, suggesting that narrower filtering could significantly increase the SNR. Finally, we demonstrate that the quantum frequency converter can operate in the quantum regime by converting a time-bin qubit and measuring the qubit fidelity after conversion.
We present a novel device for the efficient, low-noise down-conversion of low-power light from the red visible spectrum. It can be applied to interface electronic spin-qubits in nitrogen-vacancy centers in diamond to the telecommunication wavelengths and thus offers the possibility to implement large-scale quantum networks in existing fiber infrastructure. In comparison to state-of-the-art frequency converters for this application, the device presented here generates an overall noise rate, which is one order of magnitude better than current record values. Simultaneously, an internal conversion efficiency of 50 % was measured. Furthermore, the converter serves as a feasibility demonstration of a general concept for the down-conversion of light from the sub-micron spectral range to telecommunication wavelengths.
Interconnected quantum devices are the building blocks of quantum networks, where state transduction plays a central role. The frequency conversion of photons into the telecommunication C-band is decisive in taking advantage of current low-loss transmission lines. Here, we report the difference frequency conversion of 637.2 nm fluorescent light from a cluster of NV centers in diamond to tunable wavelengths between 1559.0 nm and 1564.9 nm. In order to avoid detrimental noise from spontaneous emissions, we use a two-step conversion device based on a single-pumped periodically poled lithium niobate waveguide. We observed a total external (internal) conversion efficiency of 3.0 ± 0.1 (20.5 ± 0.8) % with a noise rate of 2.4 ± 0.8 (16 ± 5) cps/GHz.