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

Photonics

Single Microwave Photon Detection with a Trapped Electron

April Cridland Mathad, John H. Lacy, Jonathan Pinder, J. Verdú

Published Nov 19, 2016• 18 citations
Publisher

Abstract

We investigate theoretically the use of an electron in a Penning trap as a detector of single microwave photons. At the University of Sussex we are developing a chip Penning trap technology, designed to be integrated within quantum circuits. Microwave photons are guided into the trap and interact with the electron’s quantum cyclotron motion. This is an electric dipole transition, where the near field of the microwave radiation induces quantum jumps of the cyclotron harmonic oscillator. The quantum jumps can be monitored using the continuous Stern-Gerlach effect, providing the quantum non demolition signal of the microwave quanta. We calculate the quantum efficiency of photon detection and discuss the main features and technical challenges for the trapped electron as a quantum microwave sensor.

DOI
10.3390/photonics3040059

Related papers

Ion-photon entanglement and state mapping in an optical cavity

Tracy E. Northup, Andreas Stute, Bernardo Casabone +3 more

At the University of Sussex we are building a coplanar-waveguide (CPW) Penning trap. This is a novel planar Penning trap, which results form the projection of the well-known cylindrical trap onto the surface of a chip [1]. The trap allows for the compensation of electrical anharmonicities up to the sixth order and permits the observation of a single trapped electron, a primary goal not yet achieved with planar Penning trap technology. The electron can be coupled to a distant superconducting coplanar-waveguide resonator, such as those used in circuit-QED with artificial two level systems. The cyclotron motion interacts coherently with the microwave resonator, implementing a system of two coupled quantum harmonic oscillators and with applications in quantum metrology and quantum computation. In the poster, we report on recent experimental progress in the construction of a cryogenic CPW- Penning trap.

Bulletin of the American Physical Society•Jun 6, 2012•0 citations

Demonstration of a Spherical Penning Trap for Single Electrons

Zirui Fang, Xing Fan

A spherical Penning trap has well-separated, clean microwave resonances, making it attractive for precision measurements of the electron magnetic moment and for dark-photon and axion searches with trapped electrons. We demonstrate single-electron trapping in a spherical Penning trap and characterize its microwave resonance structure. The design, single-electron detection, microwave mode characterization, and advantages of this geometry are presented.

physics.atom-phCross-listedarXiv:2606.03639•Jun 3, 2026

Towards the implementation of the Microwave Quantum Illumination Protocol using a trapped electron

Raquel Alvarez Garcia (7815473)

The Geonium Chip Penning trap is a planar trap that aims to reduce both the size and the cost of other conventional systems while maintaining the same level of accuracy, making it an ideal candidate for practical quantum technology applications, such as the implementation of the Microwave Quantum Illumination Protocol. This is possible thanks to the possibility of using a single electron trapped in the Geonium Chip as the emitter and receiver of single microwave photons, as well as to facilitate the creation and detection of quantum correlations. The results presented in this thesis consist on the first steps towards the engineering of a scalable and deployable system, adapted to the requirements of the Quantum Illumination Protocol. This thesis has tackled all the aspects associated to this task, such as studies on how to enhance the quantum efficiency of single microwave photons using a trapped electron, the engineering and characterisation of a novel LED-based electron source which will help to reduce the overall size of the experiment and the first steps towards the development of a novel planar magnetic field source made of GdBCO, a high temperature superconductor.

•Jun 11, 2025•0 citations

Perspectives for Single Microwave Photon Detection

S. Pagano

The detection of single microwave photons is becoming a cornerstone of fundamental experiments in circuit quantum electrodynamics and quantum sensing. Experiments in cavity quantum electrodynamics, photon-mediated entanglement, dark-matter axion searches and quantum thermodynamics increasingly rely on single-photon sensitivity. Current technologies exploit superconducting devices, including Josephson parametric detectors, and transmon-based non-demolition counters for dark-matter haloscopes. Hybrid double quantum dot-Josephson systems reach interesting levels of efficiency, while current-biased Josephson junctions show potential for near-quantumlimited resolution. Despite impressive progress, challenges remain in reducing dark counts, improving reset speed, and scaling for multiplexed arrays. Continued advances in superconducting materials, qubit coherence, and hybrid semiconductor-superconductor designs promise to extend detection efficiency and bandwidth. These developments are poised to enable the next generation of quantum-enabled experiments, from foundational tests in quantum optics to searches for new physics.

Photonics & Electromagnetics Research Symposium - Fall (PIERS-Fall)•Nov 4, 2025•0 citations

Coherent coupling of a trapped electron to a distant superconducting microwave cavity

April Cridland Mathad, John H. Lacy, Jonathan Pinder +4 more

We theoretically investigate the coupling of a single electron in a planar Penning trap with a remote superconducting microwave (MW) cavity. Coupling frequencies around Ω=2π·1 MHz can be reached with resonators with a loaded quality factor of Q=105, allowing for the strong coupling regime. The electron and the cavity form a system of two coupled quantum harmonic oscillators. This is a hybrid and linear microwave quantum network. We show that the coherent interaction can be sustained over distances of a few mm up to several cm. Similar to classical linear MW circuits, the coherent quantum exchange of photons is ruled by the impedances of the electron and the cavity. As one concrete application, we discuss the entanglement of the cyclotron motions of two electrons located in two separate traps.

Applied Physics Letters•Oct 12, 2020•5 citations

Always-on, highly efficient microwave photon detector based on a superconducting artificial molecule

Vyom Kulkarni, Mohammed Ali Aamir, Simon Sundelin +1 more

Efficient detection of single microwave photons is a key capability for emerging quantum technologies. Yet, it remains far less developed than its optical domain counterpart. Realizing detectors that simultaneously achieve high efficiency, low dark counts, and continuous operation has proved challenging. Existing detectors operate cyclically, forcing a trade-off between efficiency and duty cycle. Here, we demonstrate a continuously operated microwave single-photon detector based on a superconducting artificial molecule. In our scheme, an incoming photon is captured by a bright state of the molecule and then transferred to a long-lived dark state via a driven-dissipative process. Photon ``clicks'' are revealed as quantum jumps in the continuously monitored dark state. We observe a cyclic detection efficiency of $0.73$, and a continuous detection efficiency of $0.47$ over a $5\,\mathrm{MHz}$ instantaneous bandwidth, with a $1\,μ\mathrm{s}$ temporal resolution and a $15\,μ\mathrm{s}$ dead time. By overcoming the trade-off between efficiency and duty cycle, this approach establishes continuous microwave photon detection for quantum sensing, quantum thermodynamics, and fundamental physics.

quant-pharXiv:2608.12972•Aug 14, 2026•0 citations
We investigate theoretically the use of an electron in a Penning trap as a detector of single microwave photons. At the University of Sussex we are developing a chip Penning trap technology, designed to be integrated within quantum circuits. Microwave photons are guided into the trap and interact with the electron’s quantum cyclotron motion. This is an electric dipole transition, where the near field of the microwave radiation induces quantum jumps of the cyclotron harmonic oscillator. The quantum jumps can be monitored using the continuous Stern-Gerlach effect, providing the quantum non demolition signal of the microwave quanta. We calculate the quantum efficiency of photon detection and discuss the main features and technical challenges for the trapped electron as a quantum microwave sensor.
At the University of Sussex we are building a coplanar-waveguide (CPW) Penning trap. This is a novel planar Penning trap, which results form the projection of the well-known cylindrical trap onto the surface of a chip [1]. The trap allows for the compensation of electrical anharmonicities up to the sixth order and permits the observation of a single trapped electron, a primary goal not yet achieved with planar Penning trap technology. The electron can be coupled to a distant superconducting coplanar-waveguide resonator, such as those used in circuit-QED with artificial two level systems. The cyclotron motion interacts coherently with the microwave resonator, implementing a system of two coupled quantum harmonic oscillators and with applications in quantum metrology and quantum computation. In the poster, we report on recent experimental progress in the construction of a cryogenic CPW- Penning trap.
The Geonium Chip Penning trap is a planar trap that aims to reduce both the size and the cost of other conventional systems while maintaining the same level of accuracy, making it an ideal candidate for practical quantum technology applications, such as the implementation of the Microwave Quantum Illumination Protocol. This is possible thanks to the possibility of using a single electron trapped in the Geonium Chip as the emitter and receiver of single microwave photons, as well as to facilitate the creation and detection of quantum correlations. The results presented in this thesis consist on the first steps towards the engineering of a scalable and deployable system, adapted to the requirements of the Quantum Illumination Protocol. This thesis has tackled all the aspects associated to this task, such as studies on how to enhance the quantum efficiency of single microwave photons using a trapped electron, the engineering and characterisation of a novel LED-based electron source which will help to reduce the overall size of the experiment and the first steps towards the development of a novel planar magnetic field source made of GdBCO, a high temperature superconductor.
The detection of single microwave photons is becoming a cornerstone of fundamental experiments in circuit quantum electrodynamics and quantum sensing. Experiments in cavity quantum electrodynamics, photon-mediated entanglement, dark-matter axion searches and quantum thermodynamics increasingly rely on single-photon sensitivity. Current technologies exploit superconducting devices, including Josephson parametric detectors, and transmon-based non-demolition counters for dark-matter haloscopes. Hybrid double quantum dot-Josephson systems reach interesting levels of efficiency, while current-biased Josephson junctions show potential for near-quantumlimited resolution. Despite impressive progress, challenges remain in reducing dark counts, improving reset speed, and scaling for multiplexed arrays. Continued advances in superconducting materials, qubit coherence, and hybrid semiconductor-superconductor designs promise to extend detection efficiency and bandwidth. These developments are poised to enable the next generation of quantum-enabled experiments, from foundational tests in quantum optics to searches for new physics.
We theoretically investigate the coupling of a single electron in a planar Penning trap with a remote superconducting microwave (MW) cavity. Coupling frequencies around Ω=2π·1 MHz can be reached with resonators with a loaded quality factor of Q=105, allowing for the strong coupling regime. The electron and the cavity form a system of two coupled quantum harmonic oscillators. This is a hybrid and linear microwave quantum network. We show that the coherent interaction can be sustained over distances of a few mm up to several cm. Similar to classical linear MW circuits, the coherent quantum exchange of photons is ruled by the impedances of the electron and the cavity. As one concrete application, we discuss the entanglement of the cyclotron motions of two electrons located in two separate traps.
Efficient detection of single microwave photons is a key capability for emerging quantum technologies. Yet, it remains far less developed than its optical domain counterpart. Realizing detectors that simultaneously achieve high efficiency, low dark counts, and continuous operation has proved challenging. Existing detectors operate cyclically, forcing a trade-off between efficiency and duty cycle. Here, we demonstrate a continuously operated microwave single-photon detector based on a superconducting artificial molecule. In our scheme, an incoming photon is captured by a bright state of the molecule and then transferred to a long-lived dark state via a driven-dissipative process. Photon ``clicks'' are revealed as quantum jumps in the continuously monitored dark state. We observe a cyclic detection efficiency of 0.730.730.73, and a continuous detection efficiency of 0.470.470.47 over a 5 MHz5\,\mathrm{MHz}5MHz instantaneous bandwidth, with a 1 μs1\,μ\mathrm{s}1μs temporal resolution and a 15 μs15\,μ\mathrm{s}15μs dead time. By overcoming the trade-off between efficiency and duty cycle, this approach establishes continuous microwave photon detection for quantum sensing, quantum thermodynamics, and fundamental physics.