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:2608.18692

Nonlinear collective dynamics and microwave comb generation in a diamond maser

Christoph W. Zollitsch, Jonas N. Bach, Christopher W. M. Kay, Jonathan D. Breeze

physics.opticsquant-phSubmitted Aug 19, 2026• Announced Aug 20, 2026• 0 citations
arXivHTMLPDF

Abstract

Optically pumped room temperature masers are a promising platform for driven dissipative spin photon physics beyond steady state emission. Here we observe a sequence of dynamical thresholds in a room temperature nitrogen vacancy diamond maser as the optical pump is increased above the conventional masing threshold. The first threshold yields narrow-line continuous wave emission, while a second threshold produces a periodic train of microwave pulses whose repetition rate generates a frequency comb spectrum. At higher pump power, a third threshold gives rise to pulses with an oscillatory, frequency chirped decay. Time-resolved measurements link the comb directly to self-pulsing dynamics and Fourier analysis of individual bursts reveals a broad distribution of frequencies consistent with collective spin-resonator dynamics in an inhomogeneously broadened ensemble. These results establish the diamond maser as a room temperature platform for nonlinear nonequilibrium light matter dynamics and microwave comb generation.

Related papers

Quantum theory of the diamond maser: Stimulated and superradiant emission

Christoph W. Zollitsch, Jonathan Breeze

We present a quantum theory of diamond masers operating at any temperature using a cavity quantum electrodynamical framework. Special attention is paid to the recently demonstrated room-temperature solid-state masers based on nitrogen-vacancy (NV) defect centers in diamond, but the model can easily be modified for other photoexcited chromophores such as pentacene-doped paraterphenyl, vacancies in silicon-carbide or boron nitride. We show that the eight energy levels involved in the optically pumped NV center polarization process can be mapped to a simple pumped two-level-system. We then derive simple analytical expressions for the optical pump threshold condition for masing as well as the steady-state microwave output power which can be used to design and predict maser performance. Finally, we investigate second-order correlations and find that typical diamond masers operate in an intermediate regime between the good and bad cavity limits where photon emission is driven by both stimulated and superradiant processes.

Physical Review A•May 14, 2025•2 citations

Room-temperature inversionless diamond nitrogen-vacancy electronic spin maser

Ali Fawaz, Sarath Raman Nair

We propose a method to create a room-temperature maser operating at approximately 2.9~GHz frequency using an ensemble of negatively charged nitrogen-vacancy electronic spins (NV) in diamond, without requiring population inversion. Our method considers a DC magnetic field of a few milli-Tesla (mT) applied along the perpendicular direction of an ensemble of NV spins aligned along a common axis. This perpendicular magnetic-field creates superposition states of $|m_{\mathrm{s}}=-1\rangle$ and $|m_{\mathrm{s}}=+1\rangle$ of the NV spin's ground state triplet levels and thereby makes it possible to drive all three transitions in the NV spin ground state. We model the system by including optical pumping of the NV spins, near-resonant driving of two transitions, and coupling the third transition to a near-resonant microwave resonator. Numerical estimates using experimentally realizable parameters show that inversionless masing can be achieved inside the microwave resonator using our method. As an application, we show that the output intensity of an inversionless maser ($1.1\times10^{14}$ spins) can be used for magnetic field sensing with a DC sensitivity on the order of a hundred pT/$\sqrt{\mathrm{Hz}}$. Our study opens a new direction in room-temperature diamond NV maser devices for quantum technological applications without the requirement of a strong bias magnetic field, as in conventional NV diamond masers.

quant-pharXiv:2607.07124•Jul 9, 2026•0 citations

Proposal for a room-temperature diamond maser

L. Jin, Matthias Pfender, Nabeel Aslam +4 more

The application of masers is limited by its demanding working conditions (high vacuum or low temperature). A room-temperature solid-state maser is highly desirable, but the lifetimes of emitters (electron spins) in solids at room temperature are usually too short (∼ns) for population inversion. Masing from pentacene spins in p-terphenyl crystals, which have a long spin lifetime (∼0.1 ms), has been demonstrated. This maser, however, operates only in the pulsed mode. Here we propose a room-temperature maser based on nitrogen-vacancy centres in diamond, which features the longest known solid-state spin lifetime (∼5 ms) at room temperature, high optical pumping efficiency (∼10(6) s(-1)) and material stability. Our numerical simulation demonstrates that a maser with a coherence time of approximately minutes is feasible under readily accessible conditions (cavity Q-factor ∼5 × 10(4), diamond size ∼3 × 3 × 0.5 mm(3) and pump power <10 W). A room-temperature diamond maser may facilitate a broad range of microwave technologies.

arXiv:1509.07909•Nature Communications•Sep 23, 2015•88 citations

Cavity Quantum Electrodynamics Effects of Optically Cooled Nitrogen-Vacancy Centers Coupled to a High Frequency Microwave Resonator

Yuan Zhang, Qilong Wu, Wu, Hao +4 more

Recent experiments demonstrated the cooling of a microwave mode of a high-quality dielectric resonator coupled to optically cooled nitrogen-vacancy (NV) spins in diamond. Our recent theoretical study [arXiv:2110.10950] pointed out the cooled NV spins can be used to realize cavity quantum electrodynamics effects (C-QED) at room temperature. In this article, we propose to modify the setup used in a recent diamond maser experiment [Nature 55, 493-496 (2018)], which features a higher spin transition frequency, a lower spin-dephasing rate and a stronger NV spins-resonator coupling, to realize better microwave mode cooling and the room-temperature CQED effects. To describe more precisely the optical spin cooling and the collective spin-resonator coupling, we extend the standard Jaynes-Cumming model to account for the rich electronic and spin levels of the NV centers. Our calculations show that for the proposed setup it is possible to cool the microwave mode from $293$ K (room temperature) to $116$ K, which is about $72$ K lower than the previous records, and to study the intriguing dynamics of the CQED effects under the weak-to-strong coupling transition by varying the laser power. With simple modifications, our model can be applied to, e.g., other solid-state spins or triplet spins of pentacene molecules, and to investigate other effects, such as the operations of pulsed and continuous-wave masing.

arXiv:2203.04102•Mar 8, 2022•0 citations

Self-induced Superradiant Masing

Kersten, W., De Zordo, N., Diekmann, O. +9 more

In cavity quantum electrodynamics (cQED) and particularly superradiance, emitters are typically assumed to be independent, interacting only through light shared via a common mode. While such photon-mediated interactions lead to a rich spectrum of collective optical effects, direct dipole-dipole interactions within the emitter ensemble are generally viewed as a source of decoherence. Here, we uncover a new role for direct spin-spin interactions as a drive for the superradiant dynamics of a hybrid system of nitrogen-vacancy center spins in diamond coupled to a superconducting microwave cavity. After an initial fast superradiant burst, we observe an unexpected train of subsequent emission pulses followed by quasi-continuous masing for up to one millisecond. We show that this surprising behavior arises from spectral hole refilling, where spin inversion is redistributed into the superradiant window of spins resonant with the cavity. We report measurements that clearly exclude other cQED-related effects, and performed microscopic simulations of up to one million spins, which demonstrate that the observed self-induced masing is indeed driven by dipole-dipole interactions between the spins. These findings open new pathways for exploring complex spin-spin interactions in dense disordered systems and offer possibilities for ultra-narrow linewidth solid-state superradiant masers powered purely by microwave-driven spin control.

•Nov 5, 2025•0 citations

Self-induced superradiant masing

Wenzel Kersten, Nikolaus de Zordo, Oliver Diekmann +9 more

In cavity quantum electrodynamics and particularly superradiance, emitters are typically assumed to be independent, interacting only through light shared via a common mode. Although such photon-mediated interactions lead to a wide range of collective optical effects, direct dipole-dipole interactions within the emitter ensemble are generally viewed as a source of decoherence. Here we report the role of direct spin-spin interactions as a drive for the superradiant dynamics of a hybrid system of nitrogen-vacancy centre spins in a diamond coupled to a superconducting microwave cavity. After an initial fast superradiant burst, we observe a train of subsequent emission pulses followed by quasi-continuous masing for up to one millisecond. We show that this behaviour arises from spectral hole refilling, where spin inversion is redistributed into the superradiant window of spins resonant with the cavity. We report measurements that exclude other cavity-related effects and perform microscopic simulations that confirm that the observed behaviour is driven by dipole-dipole interactions between the spins. These findings open pathways for exploring complex spin-spin interactions in dense disordered systems and offer possibilities for ultranarrow-linewidth solid-state superradiant masers powered purely by microwave-driven spin control.

arXiv:2402.08537•Nature Physics•Jan 1, 2026•6 citations
Optically pumped room temperature masers are a promising platform for driven dissipative spin photon physics beyond steady state emission. Here we observe a sequence of dynamical thresholds in a room temperature nitrogen vacancy diamond maser as the optical pump is increased above the conventional masing threshold. The first threshold yields narrow-line continuous wave emission, while a second threshold produces a periodic train of microwave pulses whose repetition rate generates a frequency comb spectrum. At higher pump power, a third threshold gives rise to pulses with an oscillatory, frequency chirped decay. Time-resolved measurements link the comb directly to self-pulsing dynamics and Fourier analysis of individual bursts reveals a broad distribution of frequencies consistent with collective spin-resonator dynamics in an inhomogeneously broadened ensemble. These results establish the diamond maser as a room temperature platform for nonlinear nonequilibrium light matter dynamics and microwave comb generation.
We present a quantum theory of diamond masers operating at any temperature using a cavity quantum electrodynamical framework. Special attention is paid to the recently demonstrated room-temperature solid-state masers based on nitrogen-vacancy (NV) defect centers in diamond, but the model can easily be modified for other photoexcited chromophores such as pentacene-doped paraterphenyl, vacancies in silicon-carbide or boron nitride. We show that the eight energy levels involved in the optically pumped NV center polarization process can be mapped to a simple pumped two-level-system. We then derive simple analytical expressions for the optical pump threshold condition for masing as well as the steady-state microwave output power which can be used to design and predict maser performance. Finally, we investigate second-order correlations and find that typical diamond masers operate in an intermediate regime between the good and bad cavity limits where photon emission is driven by both stimulated and superradiant processes.
We propose a method to create a room-temperature maser operating at approximately 2.9~GHz frequency using an ensemble of negatively charged nitrogen-vacancy electronic spins (NV) in diamond, without requiring population inversion. Our method considers a DC magnetic field of a few milli-Tesla (mT) applied along the perpendicular direction of an ensemble of NV spins aligned along a common axis. This perpendicular magnetic-field creates superposition states of ∣ms=−1⟩|m_{\mathrm{s}}=-1\rangle∣ms​=−1⟩ and ∣ms=+1⟩|m_{\mathrm{s}}=+1\rangle∣ms​=+1⟩ of the NV spin's ground state triplet levels and thereby makes it possible to drive all three transitions in the NV spin ground state. We model the system by including optical pumping of the NV spins, near-resonant driving of two transitions, and coupling the third transition to a near-resonant microwave resonator. Numerical estimates using experimentally realizable parameters show that inversionless masing can be achieved inside the microwave resonator using our method. As an application, we show that the output intensity of an inversionless maser (1.1×10141.1\times10^{14}1.1×1014 spins) can be used for magnetic field sensing with a DC sensitivity on the order of a hundred pT/Hz\sqrt{\mathrm{Hz}}Hz​. Our study opens a new direction in room-temperature diamond NV maser devices for quantum technological applications without the requirement of a strong bias magnetic field, as in conventional NV diamond masers.
The application of masers is limited by its demanding working conditions (high vacuum or low temperature). A room-temperature solid-state maser is highly desirable, but the lifetimes of emitters (electron spins) in solids at room temperature are usually too short (∼ns) for population inversion. Masing from pentacene spins in p-terphenyl crystals, which have a long spin lifetime (∼0.1 ms), has been demonstrated. This maser, however, operates only in the pulsed mode. Here we propose a room-temperature maser based on nitrogen-vacancy centres in diamond, which features the longest known solid-state spin lifetime (∼5 ms) at room temperature, high optical pumping efficiency (∼10(6) s(-1)) and material stability. Our numerical simulation demonstrates that a maser with a coherence time of approximately minutes is feasible under readily accessible conditions (cavity Q-factor ∼5 × 10(4), diamond size ∼3 × 3 × 0.5 mm(3) and pump power <10 W). A room-temperature diamond maser may facilitate a broad range of microwave technologies.
Recent experiments demonstrated the cooling of a microwave mode of a high-quality dielectric resonator coupled to optically cooled nitrogen-vacancy (NV) spins in diamond. Our recent theoretical study [arXiv:2110.10950] pointed out the cooled NV spins can be used to realize cavity quantum electrodynamics effects (C-QED) at room temperature. In this article, we propose to modify the setup used in a recent diamond maser experiment [Nature 55, 493-496 (2018)], which features a higher spin transition frequency, a lower spin-dephasing rate and a stronger NV spins-resonator coupling, to realize better microwave mode cooling and the room-temperature CQED effects. To describe more precisely the optical spin cooling and the collective spin-resonator coupling, we extend the standard Jaynes-Cumming model to account for the rich electronic and spin levels of the NV centers. Our calculations show that for the proposed setup it is possible to cool the microwave mode from 293293293 K (room temperature) to 116116116 K, which is about 727272 K lower than the previous records, and to study the intriguing dynamics of the CQED effects under the weak-to-strong coupling transition by varying the laser power. With simple modifications, our model can be applied to, e.g., other solid-state spins or triplet spins of pentacene molecules, and to investigate other effects, such as the operations of pulsed and continuous-wave masing.
In cavity quantum electrodynamics (cQED) and particularly superradiance, emitters are typically assumed to be independent, interacting only through light shared via a common mode. While such photon-mediated interactions lead to a rich spectrum of collective optical effects, direct dipole-dipole interactions within the emitter ensemble are generally viewed as a source of decoherence. Here, we uncover a new role for direct spin-spin interactions as a drive for the superradiant dynamics of a hybrid system of nitrogen-vacancy center spins in diamond coupled to a superconducting microwave cavity. After an initial fast superradiant burst, we observe an unexpected train of subsequent emission pulses followed by quasi-continuous masing for up to one millisecond. We show that this surprising behavior arises from spectral hole refilling, where spin inversion is redistributed into the superradiant window of spins resonant with the cavity. We report measurements that clearly exclude other cQED-related effects, and performed microscopic simulations of up to one million spins, which demonstrate that the observed self-induced masing is indeed driven by dipole-dipole interactions between the spins. These findings open new pathways for exploring complex spin-spin interactions in dense disordered systems and offer possibilities for ultra-narrow linewidth solid-state superradiant masers powered purely by microwave-driven spin control.
In cavity quantum electrodynamics and particularly superradiance, emitters are typically assumed to be independent, interacting only through light shared via a common mode. Although such photon-mediated interactions lead to a wide range of collective optical effects, direct dipole-dipole interactions within the emitter ensemble are generally viewed as a source of decoherence. Here we report the role of direct spin-spin interactions as a drive for the superradiant dynamics of a hybrid system of nitrogen-vacancy centre spins in a diamond coupled to a superconducting microwave cavity. After an initial fast superradiant burst, we observe a train of subsequent emission pulses followed by quasi-continuous masing for up to one millisecond. We show that this behaviour arises from spectral hole refilling, where spin inversion is redistributed into the superradiant window of spins resonant with the cavity. We report measurements that exclude other cavity-related effects and perform microscopic simulations that confirm that the observed behaviour is driven by dipole-dipole interactions between the spins. These findings open pathways for exploring complex spin-spin interactions in dense disordered systems and offer possibilities for ultranarrow-linewidth solid-state superradiant masers powered purely by microwave-driven spin control.