Watt-level coherent microwave emission from dissipation engineered solid-state quantum batteries

TL;DR

The paper addresses the challenge of achieving high-power coherent microwave generation from solid-state quantum batteries by identifying a fundamental CQED trade-off between strong spin-photon coupling for energy storage and adequate outcoupling for power delivery. It introduces dissipation engineering to temporally separate charging and discharging via dynamic control of the external cavity coupling, enabling nanosecond microwave bursts with watt-level peak power. Through simulations of three modulation schemes (instantaneous, linear, sinusoidal), the work demonstrates dramatic improvements in work extraction efficiency (over two orders of magnitude) and power compression (up to three to four orders of magnitude), with instantaneous switching delivering the best performance and the shortest pulses. This approach provides a viable path toward room-temperature, high-power coherent microwave sources based on metastable quantum batteries and establishes design principles for dynamically controlled CQED architectures.

Abstract

Recently proposed metastability-induced quantum batteries have shown particular promise for coherent microwave generation. However, achieving high-power coherent microwave generation in quantum batteries remains fundamentally challenging due to quantum correlations, aging, and self-discharging processes. For the cavity-quantum-electrodynamics (CQED)-based quantum batteries, a further trade-off arises between strong spin-photon coupling for energy storage and sufficient output coupling for power delivery. To overcome these constraints, we introduce dissipation engineering as a dynamic control strategy that temporally separates energy storage and release. By suppressing emission during charging and rapidly enhancing the output coupling during discharging, we realize nanosecond microwave bursts with watt-level peak power. By optimizing three dissipation schemes, we improve work extraction efficiency of the quantum battery by over two orders of magnitude and achieve high power compression factors outperforming the state-of-the-art techniques, establishing dissipation engineering as a pathway toward room-temperature, high-power coherent microwave sources.

Figures (10)

• Figure 1: (a) Schematic diagram of the charging and working mechanisms of the metastability-induced quantum battery. Dissipation engineering is realized by modulating the external coupling rate $\kappa_\textrm{e}$ of the microwave cavity. (b) Concept of using dissipation engineering for modulating the coherent microwave generation from the quantum battery. $N_\textrm{ph}$, microwave photon number.
• Figure 2: (a-c) Temporal evolution of the cavity total dissipation rate $\kappa$ (left axis) and the microwave photon number $N_{\mathrm{ph}}$ (right axis) under three dissipation-engineering protocols. The $\tau_\textrm{low}$ stage ends once the photon number reaches the threshold $N_{\mathrm{ph}} = 10^{10}$, after which the dissipation resets for the next cycle. The work extraction efficiency $\eta_{\mathrm{work}}$ is defined as the ratio between the photon energy change $\Delta E_{\mathrm{ph}}$ and the quantum battery energy change $\Delta E$ during each emission event, calculated from the start of the $\tau_2$ stage to the peak photon number. (d-f) Evolution of the full width at half maximum (FWHM, left axis) and maximum photon number $N_{\mathrm{ph}}^{\mathrm{(max)}}$ (right axis) for successive (the $n$th) microwave pulses under the three modulation schemes. All simulations were performed with $\tau_1=10^{-8}$ s, $\kappa_{\mathrm{low}}/2\pi=9.55 \times 10^6$ Hz, $\tau_{\mathrm{down}}=2/ \kappa_{\mathrm{low}}$, and $\tau_{\mathrm{up}}=\tau_{\mathrm{down}}$. Additional system parameters are presented in Table $1$ of Appendix B. Unless otherwise stated, all simulations adopt identical system parameters.
• Figure 3: (a-c) Temporal evolution of the output power $P_{\mathrm{out}}$ (left axis) and instantaneous power $P_{\mathrm{ins}}$ (right axis) under the three dissipation-engineering schemes. For clarity, the time scale in (a) is different from those in (b) and (c). The insets show magnified views of $P_{\mathrm{out}}$ within the organic shadow regimes. (d-f) Evolution of the FWHM of the output power $P_{\mathrm{out}}$ as well as (g-i) the work extraction efficiency $\eta_{\mathrm{work}}$ (left axis) and maximum power compression factor $\eta_{\mathrm{power}}^{(\mathrm{max})}$ (right axis, power compression factor at the maximum output power) for successive (the $n$th) microwave pulses under the three modulation schemes
• Figure 4: Dependence of the FWHMs of the intra-cavity photon number $N_{\mathrm{ph}}$ (solid lines) and the microwave output $P_\textrm{ins}$ (dashed lines), the maximum intra-cavity photon number $N_{\mathrm{ph}}^{(\mathrm{max})}$, and the maximum output power $P_{\mathrm{out}}^{(\mathrm{max})}$ on (a-c) the dissipation modulation duration $\tau_2$ and (d-f) the minimum dissipation rate $\kappa_{\mathrm{low}}$. In (a-c), the value of $\kappa_{\mathrm{low}}/2\pi$ is set to $9.55 \times 10^6$ Hz; In (d-f), the values of $\tau_2$ chosen for the instantaneous, linear and sinusoidal schemes are 440, 505 and 500 ns respectively, which yield the maximum $P_{\mathrm{out}}^{(\mathrm{max})}$ in (c).
• Figure 5: (a,b) The work extraction efficiency $\eta_{\mathrm{work}}$ and (c,d) maximum power compression factor $\eta_{\mathrm{power}}^{(\mathrm{max})}$ depending on $\tau_2$ and $\kappa_{\mathrm{low}}$. In (b) and (d), $\tau_2$ of the instantaneous, linear, and sinusoidal schemes are 440, 505 and 500 ns respectively.