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

arXiv:2410.14278 · Physical Review Research

Wigner-function formalism for the detection of single microwave pulses in a resonator-coupled double quantum dot

Drilon Zenelaj, Peter Samuelsson, Patrick P. Potts

Published Mar 24, 2025• 3 citations
arXivHTMLPDF

Abstract

Semiconductor double quantum dots (DQD) coupled to superconducting microwave resonators offer a promising platform for the detection of single microwave photons. In previous works, the photodetection was studied for a monochromatic source of microwave photons. Here, we theoretically analyze the photodetection of single microwave pulses. The photodetection in this case can be seen as a nonlinear filtering process of an incoming signal, the pulse, to an outgoing one, the photocurrent. This analogy to signal processing motivated the derivation of a Wigner-function formalism which provides a compelling visualization of the time and frequency properties of the photodetector for low intensities. We find a trade-off between detecting the time and the frequency of the incoming photons, in agreement with the time-energy uncertainty relation. As the intensity of the source increases, the photodetection is influenced by coherent Rabi oscillations of the DQD. Our findings give insight into the time-dependent properties of microwave photons interacting with electrons in a DQD-resonator hybrid system and provide guidance for experiments on single microwave pulse detection.

DOI
10.1103/physrevresearch.7.013305

Related papers

Strong Charge-Photon Coupling and High-Efficiency Microwave Photodetection in Hybrid Quantum Dot-Resonator Systems

Oppliger, Fabian

This thesis investigates hybrid circuit quantum electrodynamics (cQED) as a versatile platform that unites superconducting resonators with semiconductor quantum dots. The central motivation is to harness strong light-matter coupling at the single-photon level, which enables coherent photon-qubit interactions and paves the way for quantum technologies in computation, communication, and sensing. The first part of this work combines hybrid cQED with holes in planar Ge/SiGe, a material system that has only recently become accessible for quantum devices. Planar Ge offers unique advantages for this purpose and has attracted considerable attention in the context of quantum computing. In contrast, its potential for hybrid cQED has remained largely unexplored, making the present work one of the first demonstrations of strong light-matter interaction in this platform. Within this framework, we demonstrate strong charge-photon coupling in planar Ge by observing vacuum Rabi splitting between a hole charge qubit based on a double quantum dot (DQD) and a microwave resonator. We employ a frequency-tunable high-impedance resonator to perform qubit spectroscopy, enabling systematic exploration of coupling regimes and confirming device controllability. In addition, we use this setup to carry out excited-state spectroscopy of strongly correlated states in the DQD, revealing the formation of Wigner molecules and illustrating how the hybrid architecture can be harnessed to access many-body physics. While these experiments in Ge demonstrate how strong coupling can be harnessed to explore qubit physics and correlated states, they also exemplify the wider potential of hybrid cQED. A particularly pressing application is in quantum optics, where efficient single-photon detectors are still lacking in the microwave regime. Such detectors are essential for enabling experiments in quantum communication and microwave quantum optics. In the second part of this thesis, we address this challenge by realizing a photodetector based on a GaAs DQD coupled to a superconducting resonator. The detector operates via photon-to-charge conversion and achieves efficiencies approaching unity. Strong coupling plays a central role by ensuring that incoming photons are absorbed before being lost to the environment, which is key to the high performance of the detector. We further exploit the frequency tunability of the resonator to investigate device performance and identify the parameters that optimize detection efficiency. The broader impact of this work lies in advancing quantum technologies that rely on coherent microwave photons. Applications include spin qubit readout, long-distance photon-mediated coupling, quantum communication, and microwave quantum optics. Looking forward, planar Ge is identified as a highly competitive platform for hybrid cQED. Future directions include the development of single-photon sources, quantum- limited detectors, and analog quantum simulators based on engineered resonator-qubit arrays.

•Jan 1, 2025•0 citations

Single-electron double quantum dot dipole-coupled to a single photonic mode

J. Basset, David-Dominik Jarausch, Anna Stockklauser +6 more

We have realized a hybrid solid-state quantum device in which a single-electron semiconductor double quantum dot is dipole coupled to a superconducting microwave frequency transmission line resonator. The dipolar interaction between the two entities manifests itself via dispersive and dissipative effects observed as frequency shifts and linewidth broadenings of the photonic mode respectively. A Jaynes-Cummings Hamiltonian master equation calculation is used to model the combined system response and allows for determining both the coherence properties of the double quantum dot and its interdot tunnel coupling with high accuracy. The value and uncertainty of the tunnel coupling extracted from the microwave read-out technique are compared to a standard quantum point contact charge detection analysis. The two techniques are found to be consistent with a superior precision for the microwave experiment when tunneling rates approach the resonator eigenfrequency. Decoherence properties of the double dot are further investigated as a function of the number of electrons inside the dots. They are found to be similar in the single-electron and many-electron regimes suggesting that the density of the confinement energy spectrum plays a minor role in the decoherence rate of the system under investigation.

arXiv:1304.5141•Physical Review B•Sep 30, 2013•71 citations

High-efficiency microwave photodetection by cavity-coupled double quantum dots with single-cavity-photon sensitivity

Subhomoy Haldar, Harald Havir, Waqar Hussain Khan +6 more

We present a superconducting cavity-coupled double quantum dot (DQD) photodiode that achieves a maximum photon-to-electron conversion efficiency of 25% in the microwave domain. With a higher-quality-factor cavity and improved device design to prevent photon leakages through unwanted pathways, our device measures microwave signals down to the 100-aW power level and achieves sensitivity to probe microwave signals with one photon at a time in the cavity. We analyze the photodiode operation using the Jaynes-Cummings input-output theory, identifying the key improvements of stronger cavity-DQD coupling needed to achieve near-unity photodetection efficiency. The results presented in this work represent a crucial advancement toward near-unity microwave photodetection efficiency with single-cavity-photon sensitivity.

arXiv:2406.03047•Physical Review Applied•Sep 29, 2025•6 citations

Quantum efficiency of a single microwave photon detector based on a semiconductor double quantum dot

Clement H. Wong, Maxim Vavilov

Motivated by recent interest in implementing circuit quantum electrodynamics with semiconducting quantum dots, we consider a double quantum dot (DQD) capacitively coupled to a superconducting resonator that is driven by the microwave field of a superconducting transmission line. We analyze the DQD current response using input-output theory and show that the resonator-coupled DQD is a sensitive microwave single photon detector. Using currently available experimental parameters of DQD-resonator coupling and dissipation, including the effects of $1/f$ charge noise and phonon noise, we determine the parameter regime for which incident photons are completely absorbed and near-unit $\ensuremath{\gtrsim}98$% efficiency can be achieved. We show that this regime can be reached by using very high quality resonators with quality factor $Q\ensuremath{\simeq}{10}^{5}$.

arXiv:1512.06939•Physical Review A•Jan 24, 2017•46 citations

Optimal dispersive readout of a spin qubit with a microwave resonator

Benjamin D’Anjou, Guido Burkard

Strong coupling of semiconductor spin qubits to superconducting microwave resonators was recently demonstrated [X. Mi et al., Nature 555, 599 (2018); A. J. Landig et al., Nature 560, 179 (2018); N. Samkharadze et al., Science 359, 1123 (2018); T. Cubaynes et al., NPJ Quant. Inf. 5, 47 (2019)]. These breakthroughs pave the way for quantum information processing that combines the long coherence times of solid-state spin qubits with the long-distance connectivity, fast control, and fast high-fidelity quantum-non-demolition readout of existing superconducting qubit implementations. Here we theoretically analyze and optimize the dispersive readout of a single spin in a semiconductor double quantum dot (DQD) coupled to a microwave resonator via its electric dipole moment. The strong spin-photon coupling arises from the motion of the electron spin in a local magnetic field gradient. We calculate the signal-to-noise ratio (SNR) of the readout accounting for both Purcell spin relaxation and spin relaxation arising from intrinsic electric noise within the semiconductor. We express the maximum achievable SNR in terms of the cooperativity associated with these two dissipation processes. We find that while the cooperativity increases with the strength of the dipole coupling between the DQD and the resonator, it does not depend on the strength of the magnetic field gradient. We then optimize the SNR as a function of experimentally tunable DQD parameters. We identify wide regions of parameter space where the unwanted backaction of the resonator photons on the qubit is small. Moreover, we find that the coupling of the resonator to other DQD transitions can enhance the SNR by at least a factor of two, a ``straddling'' effect [J. Koch et al., Phys. Rev. A 76, 042319 (2007)] that occurs only at nonzero energy detuning of the DQD double-well potential. We estimate that with current technology, single-shot readout fidelities in the range 82--95% can be achieved within a few $\ensuremath{\mu}\mathrm{s}$ of readout time without requiring the use of Purcell filters.

arXiv:1905.09702•Physical review. B./Physical review. B•Dec 23, 2019•45 citations

Microwave-Resonator-Detected Excited-State Spectroscopy of a Double Quantum Dot

Ming-Bo Chen, Shun-Li Jiang, Ning Wang +6 more

As an application in circuit quantum electrodynamics coupled systems, superconducting resonators play an important role in high-sensitivity measurements in a superconducting-semiconductor hybrid architecture. Taking advantage of a high-impedance $\mathrm{Nb}\text{\ensuremath{-}}\mathrm{Ti}\text{\ensuremath{-}}\mathrm{N}$ resonator, we perform excited-state spectroscopy on a $\mathrm{Ga}\mathrm{As}$ double quantum dot (DQD) by applying voltage pulses to one gate electrode. The pulse train modulates the DQD energy detuning and gives rise to charge state transitions at zero detuning. Benefiting from the outstanding sensitivity of the resonator, we distinguish different spin-state transitions in the energy spectrum according to the Pauli exclusion principle. Furthermore, we experimentally study how the interdot tunneling rate modifies the resonator response. The experimental results are consistent with the simulated spectra based on our model.

arXiv:2102.08169•Physical Review Applied•Apr 28, 2021•11 citations
Semiconductor double quantum dots (DQD) coupled to superconducting microwave resonators offer a promising platform for the detection of single microwave photons. In previous works, the photodetection was studied for a monochromatic source of microwave photons. Here, we theoretically analyze the photodetection of single microwave pulses. The photodetection in this case can be seen as a nonlinear filtering process of an incoming signal, the pulse, to an outgoing one, the photocurrent. This analogy to signal processing motivated the derivation of a Wigner-function formalism which provides a compelling visualization of the time and frequency properties of the photodetector for low intensities. We find a trade-off between detecting the time and the frequency of the incoming photons, in agreement with the time-energy uncertainty relation. As the intensity of the source increases, the photodetection is influenced by coherent Rabi oscillations of the DQD. Our findings give insight into the time-dependent properties of microwave photons interacting with electrons in a DQD-resonator hybrid system and provide guidance for experiments on single microwave pulse detection.
This thesis investigates hybrid circuit quantum electrodynamics (cQED) as a versatile platform that unites superconducting resonators with semiconductor quantum dots. The central motivation is to harness strong light-matter coupling at the single-photon level, which enables coherent photon-qubit interactions and paves the way for quantum technologies in computation, communication, and sensing. The first part of this work combines hybrid cQED with holes in planar Ge/SiGe, a material system that has only recently become accessible for quantum devices. Planar Ge offers unique advantages for this purpose and has attracted considerable attention in the context of quantum computing. In contrast, its potential for hybrid cQED has remained largely unexplored, making the present work one of the first demonstrations of strong light-matter interaction in this platform. Within this framework, we demonstrate strong charge-photon coupling in planar Ge by observing vacuum Rabi splitting between a hole charge qubit based on a double quantum dot (DQD) and a microwave resonator. We employ a frequency-tunable high-impedance resonator to perform qubit spectroscopy, enabling systematic exploration of coupling regimes and confirming device controllability. In addition, we use this setup to carry out excited-state spectroscopy of strongly correlated states in the DQD, revealing the formation of Wigner molecules and illustrating how the hybrid architecture can be harnessed to access many-body physics. While these experiments in Ge demonstrate how strong coupling can be harnessed to explore qubit physics and correlated states, they also exemplify the wider potential of hybrid cQED. A particularly pressing application is in quantum optics, where efficient single-photon detectors are still lacking in the microwave regime. Such detectors are essential for enabling experiments in quantum communication and microwave quantum optics. In the second part of this thesis, we address this challenge by realizing a photodetector based on a GaAs DQD coupled to a superconducting resonator. The detector operates via photon-to-charge conversion and achieves efficiencies approaching unity. Strong coupling plays a central role by ensuring that incoming photons are absorbed before being lost to the environment, which is key to the high performance of the detector. We further exploit the frequency tunability of the resonator to investigate device performance and identify the parameters that optimize detection efficiency. The broader impact of this work lies in advancing quantum technologies that rely on coherent microwave photons. Applications include spin qubit readout, long-distance photon-mediated coupling, quantum communication, and microwave quantum optics. Looking forward, planar Ge is identified as a highly competitive platform for hybrid cQED. Future directions include the development of single-photon sources, quantum- limited detectors, and analog quantum simulators based on engineered resonator-qubit arrays.
We have realized a hybrid solid-state quantum device in which a single-electron semiconductor double quantum dot is dipole coupled to a superconducting microwave frequency transmission line resonator. The dipolar interaction between the two entities manifests itself via dispersive and dissipative effects observed as frequency shifts and linewidth broadenings of the photonic mode respectively. A Jaynes-Cummings Hamiltonian master equation calculation is used to model the combined system response and allows for determining both the coherence properties of the double quantum dot and its interdot tunnel coupling with high accuracy. The value and uncertainty of the tunnel coupling extracted from the microwave read-out technique are compared to a standard quantum point contact charge detection analysis. The two techniques are found to be consistent with a superior precision for the microwave experiment when tunneling rates approach the resonator eigenfrequency. Decoherence properties of the double dot are further investigated as a function of the number of electrons inside the dots. They are found to be similar in the single-electron and many-electron regimes suggesting that the density of the confinement energy spectrum plays a minor role in the decoherence rate of the system under investigation.
We present a superconducting cavity-coupled double quantum dot (DQD) photodiode that achieves a maximum photon-to-electron conversion efficiency of 25% in the microwave domain. With a higher-quality-factor cavity and improved device design to prevent photon leakages through unwanted pathways, our device measures microwave signals down to the 100-aW power level and achieves sensitivity to probe microwave signals with one photon at a time in the cavity. We analyze the photodiode operation using the Jaynes-Cummings input-output theory, identifying the key improvements of stronger cavity-DQD coupling needed to achieve near-unity photodetection efficiency. The results presented in this work represent a crucial advancement toward near-unity microwave photodetection efficiency with single-cavity-photon sensitivity.
Motivated by recent interest in implementing circuit quantum electrodynamics with semiconducting quantum dots, we consider a double quantum dot (DQD) capacitively coupled to a superconducting resonator that is driven by the microwave field of a superconducting transmission line. We analyze the DQD current response using input-output theory and show that the resonator-coupled DQD is a sensitive microwave single photon detector. Using currently available experimental parameters of DQD-resonator coupling and dissipation, including the effects of 1/f1/f1/f charge noise and phonon noise, we determine the parameter regime for which incident photons are completely absorbed and near-unit $\ensuremath{\gtrsim}98$% efficiency can be achieved. We show that this regime can be reached by using very high quality resonators with quality factor $Q\ensuremath{\simeq}{10}^{5}$.
Strong coupling of semiconductor spin qubits to superconducting microwave resonators was recently demonstrated [X. Mi et al., Nature 555, 599 (2018); A. J. Landig et al., Nature 560, 179 (2018); N. Samkharadze et al., Science 359, 1123 (2018); T. Cubaynes et al., NPJ Quant. Inf. 5, 47 (2019)]. These breakthroughs pave the way for quantum information processing that combines the long coherence times of solid-state spin qubits with the long-distance connectivity, fast control, and fast high-fidelity quantum-non-demolition readout of existing superconducting qubit implementations. Here we theoretically analyze and optimize the dispersive readout of a single spin in a semiconductor double quantum dot (DQD) coupled to a microwave resonator via its electric dipole moment. The strong spin-photon coupling arises from the motion of the electron spin in a local magnetic field gradient. We calculate the signal-to-noise ratio (SNR) of the readout accounting for both Purcell spin relaxation and spin relaxation arising from intrinsic electric noise within the semiconductor. We express the maximum achievable SNR in terms of the cooperativity associated with these two dissipation processes. We find that while the cooperativity increases with the strength of the dipole coupling between the DQD and the resonator, it does not depend on the strength of the magnetic field gradient. We then optimize the SNR as a function of experimentally tunable DQD parameters. We identify wide regions of parameter space where the unwanted backaction of the resonator photons on the qubit is small. Moreover, we find that the coupling of the resonator to other DQD transitions can enhance the SNR by at least a factor of two, a ``straddling'' effect [J. Koch et al., Phys. Rev. A 76, 042319 (2007)] that occurs only at nonzero energy detuning of the DQD double-well potential. We estimate that with current technology, single-shot readout fidelities in the range 82--95% can be achieved within a few $\ensuremath{\mu}\mathrm{s}$ of readout time without requiring the use of Purcell filters.
As an application in circuit quantum electrodynamics coupled systems, superconducting resonators play an important role in high-sensitivity measurements in a superconducting-semiconductor hybrid architecture. Taking advantage of a high-impedance $\mathrm{Nb}\text{\ensuremath{-}}\mathrm{Ti}\text{\ensuremath{-}}\mathrm{N}$ resonator, we perform excited-state spectroscopy on a GaAs\mathrm{Ga}\mathrm{As}GaAs double quantum dot (DQD) by applying voltage pulses to one gate electrode. The pulse train modulates the DQD energy detuning and gives rise to charge state transitions at zero detuning. Benefiting from the outstanding sensitivity of the resonator, we distinguish different spin-state transitions in the energy spectrum according to the Pauli exclusion principle. Furthermore, we experimentally study how the interdot tunneling rate modifies the resonator response. The experimental results are consistent with the simulated spectra based on our model.