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 Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)

A Cavity-Integrated High-Speed Low-Loss Optical Switch in Rubidium Vapour

Georgia Booton, Cameron McGarry, Tabijah Wasawo, Alex O. C. Davis, Kristina R. Rusimova, J. Nunn, Peter J. Mosley

Published Jun 23, 2025• 1 citation
Publisher

Abstract

The ability to dynamically route and manage optical signals at high speeds with low-loss is a substantial challenge in quantum optics. Existing optical switches, such as electro-optic phase modulators either achieve high-speed or low insertion losses, but rarely both. However, optically-controlled phase modulation in atomic vapour promises a pathway for efficient, high-bandwidth switching [1]. These characteristics are critical for single photon multiplexing in quantum technologies, implementing loop memory schemes and addressing scalability challenges in photonic quantum computation [2]. We present a cavity based system that can deliver high-speed all-optical switching of a signal field with minimal loss by accessing the strong two photon absorption in warm rubidium vapour via a counter-propagating control field.

DOI
10.1109/cleo/europe-eqec65582.2025.11109440

Related papers

Cavity-based optical switching via phase modulation in warm rubidium vapor

Georgia Booton, Tabijah Wasawo, W. O. C. Davis +5 more

Optical switching remains a key outstanding challenge for scalable photonic quantum computing due to the trade-off between speed, bandwidth, and loss. Quantum photonics demands all three to enable high computational clock rates and resource-efficient scaling to large systems. We present a cavity-based optical switch that overcomes this limitation, demonstrating a rise time of 22 ns, an insertion loss of 2.4 dB, and an extinction ratio of 17.5, which bridges the gap between speed and efficiency in photonic switching. All-optical control is achieved via phase modulation of a signal field detuned from the near-degenerate two-photon absorption ladder in warm rubidium vapor. The ultimate performance of our switch will find applications in active multiplexing, loop-based quantum memory, and feed-forward for quantum error-correction protocols.

arXiv:2508.06255•Physical Review A•Apr 28, 2026•0 citations

Fast, low-loss, all-optical phase modulation in warm rubidium vapour

William O C Davis, Paul Burdekin, Tabijah Wasawo +4 more

Abstract Low-loss high-speed switches are an integral component of future photonic quantum technologies, with applications in state generation, multiplexing, and the implementation of quantum gates. Phase modulation is one method of achieving this switching; however, existing optical phase modulators offer either high bandwidth or low loss—not both. We demonstrate fast (100 MHz bandwidth), low-loss ( 83 ( 2 ) % transmission) phase shifting ( Δ ϕ = ( 0.90 ( 5 ) ) π ) in a signal field, induced by a control field, and mediated by the two-photon 5 S 1 / 2 → 5 P 3 / 2 → 5 D 5 / 2 transition in 87 Rb vapour. The all-optical nature of the scheme circumvents restrictions of electronic phase modulators, where bandwidth and repetition rate can be limited by the requirement to rapidly modulate high voltages. We discuss routes to enhance both performance and scalability for application to a range of quantum and classical technologies.

arXiv:2309.04313•Quantum Science and Technology•Dec 16, 2024•5 citations

High-speed high-efficiency all-optical switching in rubidium vapour

Georgia Booton, Cameron McGarry, Tabijah Wasawo +5 more

Scalable photonic quantum platforms require a fast, low-loss switch to re-route photons whilst preserving their quantum state. We show light-matter interactions can deliver all-optical high-bandwidth switching with minimal loss in warm rubidium vapour.

Frontiers in Optics•Jan 1, 2025•0 citations

Two routes towards fibre-integrated optical switching with single photons

Cameron McGarry, Tabijah Wasawo, W.O. Davis +5 more

A fast, low-loss optical switch would be a powerful tool for photonic quantum technologies, allowing the implementation of, for example, rapid quantum logic gates, loop memories, and improved heralded single photon sources. Integration into optical fibre promises an avenue to future scalability, but existing optical switches cannot achieve both high speed and high efficiency. Here I present two routes to fibre-integrated, low -loss and fast optical switching. The first uses the acousto-optic effect in a tapered fibre. We demonstrate that light in the tapered region of the fibre can be coupled between optical modes by an acoustic wave, which introduces a phase-shift. The second route is by a two-photon transition in rubidium vapour. A strong control field modulates the mode of a weak signal field. We demonstrate this effect with low loss (1dB) and on short timescales (100MHz) in bulk optics, and work towards a fibre-integrated vapour cell.

Quantum Computing, Communication, and Simulation•Mar 13, 2024•0 citations

Towards single-photon switching via two-photon absorption in Rb vapor

Tabijah Wasawo, Carlo Page, Alex O. C. Davis +2 more

Strong nonlinearities mediated by atomic vapours have the potential to achieve optically controlled switching at room temperature, opening the way to scalable quantum computing. A strong candidate for engineering such interactions is the combination of optical waveguides and cavities with warm alkali vapours. Here we report the implementation of a doubly resonant cavity that translates Kerr nonlinearity induced by an optical control field into a switch for a signal field. We investigate losses and consider optimised designs. We discuss this model in the context of building practical switching devices with applications to logic gate operations at room temperature.

Quantum Computing, Communication, and Simulation•Mar 8, 2023•0 citations

Low-loss all-optical ns-switching for single-photon routing in scalable integrated quantum photonics

Fabian Ruf, Lars Nielsen, Mircea Balauroiu +2 more

Efficient single-photon routing and switching are crucial for optical quantum computing and communication. For this purpose, all-optical switches are designed for gigahertz bandwidths. The switching mechanism is based on the optical Kerr effect via cross-phase modulation (CPM) of the single-photon signal by a strong 1550-nm pump pulse. For energy-efficient switching, this nonlinear effect is exploited in a microresonator that can either be used directly as an intensity switch in a typical add–drop configuration or as a phase shifter in a Mach–Zehnder interferometer (MZI) structure. To speed up resonance build-up and quenching, a pre-emphasis build and an off-resonance wipe pulse are used. The proposed designs are verified by traveling-wave simulations which demonstrate that 0.1 dB insertion loss and ~1 ns switching windows can be achieved. For a scalable out-of-the-lab transfer, we investigate the feasibility of the proposed switch designs for fabrication in a mature photonic integrated circuit (PIC) platform. In particular, silicon nitride PICs have demonstrated record-low losses which makes them suitable for single-photon applications. By parametric modelling of the microresonator’s directional couplers based on Lumerical EME and 2.5-dimensional varFDTD simulations, the required power transmission coefficients for both signal and pump wavelength can be achieved. This results in an all-optical switch design ready for fabrication in a commercial PIC foundry which can potentially enable scalable architectures for quantum photonic applications.

Integrated Photonics Platforms•May 26, 2022•3 citations
The ability to dynamically route and manage optical signals at high speeds with low-loss is a substantial challenge in quantum optics. Existing optical switches, such as electro-optic phase modulators either achieve high-speed or low insertion losses, but rarely both. However, optically-controlled phase modulation in atomic vapour promises a pathway for efficient, high-bandwidth switching [1]. These characteristics are critical for single photon multiplexing in quantum technologies, implementing loop memory schemes and addressing scalability challenges in photonic quantum computation [2]. We present a cavity based system that can deliver high-speed all-optical switching of a signal field with minimal loss by accessing the strong two photon absorption in warm rubidium vapour via a counter-propagating control field.
Optical switching remains a key outstanding challenge for scalable photonic quantum computing due to the trade-off between speed, bandwidth, and loss. Quantum photonics demands all three to enable high computational clock rates and resource-efficient scaling to large systems. We present a cavity-based optical switch that overcomes this limitation, demonstrating a rise time of 22 ns, an insertion loss of 2.4 dB, and an extinction ratio of 17.5, which bridges the gap between speed and efficiency in photonic switching. All-optical control is achieved via phase modulation of a signal field detuned from the near-degenerate two-photon absorption ladder in warm rubidium vapor. The ultimate performance of our switch will find applications in active multiplexing, loop-based quantum memory, and feed-forward for quantum error-correction protocols.
Abstract Low-loss high-speed switches are an integral component of future photonic quantum technologies, with applications in state generation, multiplexing, and the implementation of quantum gates. Phase modulation is one method of achieving this switching; however, existing optical phase modulators offer either high bandwidth or low loss—not both. We demonstrate fast (100 MHz bandwidth), low-loss ( 83 ( 2 ) % transmission) phase shifting ( Δ ϕ = ( 0.90 ( 5 ) ) π ) in a signal field, induced by a control field, and mediated by the two-photon 5 S 1 / 2 → 5 P 3 / 2 → 5 D 5 / 2 transition in 87 Rb vapour. The all-optical nature of the scheme circumvents restrictions of electronic phase modulators, where bandwidth and repetition rate can be limited by the requirement to rapidly modulate high voltages. We discuss routes to enhance both performance and scalability for application to a range of quantum and classical technologies.
A fast, low-loss optical switch would be a powerful tool for photonic quantum technologies, allowing the implementation of, for example, rapid quantum logic gates, loop memories, and improved heralded single photon sources. Integration into optical fibre promises an avenue to future scalability, but existing optical switches cannot achieve both high speed and high efficiency. Here I present two routes to fibre-integrated, low -loss and fast optical switching. The first uses the acousto-optic effect in a tapered fibre. We demonstrate that light in the tapered region of the fibre can be coupled between optical modes by an acoustic wave, which introduces a phase-shift. The second route is by a two-photon transition in rubidium vapour. A strong control field modulates the mode of a weak signal field. We demonstrate this effect with low loss (1dB) and on short timescales (100MHz) in bulk optics, and work towards a fibre-integrated vapour cell.
Strong nonlinearities mediated by atomic vapours have the potential to achieve optically controlled switching at room temperature, opening the way to scalable quantum computing. A strong candidate for engineering such interactions is the combination of optical waveguides and cavities with warm alkali vapours. Here we report the implementation of a doubly resonant cavity that translates Kerr nonlinearity induced by an optical control field into a switch for a signal field. We investigate losses and consider optimised designs. We discuss this model in the context of building practical switching devices with applications to logic gate operations at room temperature.
Efficient single-photon routing and switching are crucial for optical quantum computing and communication. For this purpose, all-optical switches are designed for gigahertz bandwidths. The switching mechanism is based on the optical Kerr effect via cross-phase modulation (CPM) of the single-photon signal by a strong 1550-nm pump pulse. For energy-efficient switching, this nonlinear effect is exploited in a microresonator that can either be used directly as an intensity switch in a typical add–drop configuration or as a phase shifter in a Mach–Zehnder interferometer (MZI) structure. To speed up resonance build-up and quenching, a pre-emphasis build and an off-resonance wipe pulse are used. The proposed designs are verified by traveling-wave simulations which demonstrate that 0.1 dB insertion loss and ~1 ns switching windows can be achieved. For a scalable out-of-the-lab transfer, we investigate the feasibility of the proposed switch designs for fabrication in a mature photonic integrated circuit (PIC) platform. In particular, silicon nitride PICs have demonstrated record-low losses which makes them suitable for single-photon applications. By parametric modelling of the microresonator’s directional couplers based on Lumerical EME and 2.5-dimensional varFDTD simulations, the required power transmission coefficients for both signal and pump wavelength can be achieved. This results in an all-optical switch design ready for fabrication in a commercial PIC foundry which can potentially enable scalable architectures for quantum photonic applications.