arXiv subjects

X. N. Feng

Publications and source records attributed to X. N. Feng.

6 recordsLinked to original sources

arXiv2026

Significantly enhanced detectability of dark photons with a steady-state excited microwave cavity

The resonant cavity system has been widely used to search for the electromagnetic response of dark photons, although its achievable detection sensitivity remains at a relatively low level. In this letter, we propose a feasible approach to significantly improve its achievable detection sensitivity by enhancing the detectability of the dark photon-photon dynamical effect, assisted with the steady-state excitation of the target mode in the cavity. Unlike in almost all the previous detection schemes, wherein where the cavity modes are kept in vacuum (and thus only the second-order energy signals can be detected), here the pre-excited steady-state field in the cavity can be used to achieve the coherent amplification of the dark photon response signal, thereby obtaining detectable first-order (rather than the conventional second-order) energy response signals of dark photons. Although the phase of the dark photon field and thus its electromagnetic response signal is stochastic, the amplitude of such a first-order energy response power signal can still be extracted by using mature IQ demodulation technology. As a consequence, we argue that, even considering the influence of the shot noise of the pre-excited steady-state field, the achievable detection sensitivity of this in-situ enhancement detectability, based on the steady-state excitation signal of the target mode, is still at least one order of magnitude higher than those of the current resonant cavity experiments with the same Q-quality factors. Based on existing microwave cavity and weak signal demodulation detection technologies, the feasibility of such a significantly enhanced detectability scheme is also discussed.

physics.optics↗

arXiv2025

Switchable coherent state stored quantum batteries with large ergotropies

Quantum battery (QB) is a conceptually new energy storage and conversion device, which consists usually of a quantum charger and an energy store (called usually as the QB for simplicity). The demonstrated advantage of QB, over its classical counterpart, is that its charging efficiency can be significantly enhanced by using quantum entanglement resources. In this letter, we investigate alternatively how to realize the switchable charging and the lossless power detection of the charged QB. With the proposed QB configuration we show that, by adjusting the eigenfrequency of the qubit-based charger, the cavity-based QB can be switched on between the charging and power-off states and its stored energy can be non-destructively monitored by probing the transmitted spectrum of the external electromagnetic waves scattered by the qubit-based charger. As the qubit-based charger has never been excited, the proposed cavity-based QB could directly store the coherent state energy (rather than the single-photon one) and thus possess significantly large ergotropy. The physical realization of the proposed switchable QB configuration is demonstrated specifically with the experimental circuit quantum electrodynamical devices.

quant-ph↗

arXiv2025

Quantum detection of millimeter wave electric fields with driving surface-state electrons

We introduce a spin-based receiver to sensitively detect the electric fields of millimeter (mm) waves by using quantum interferometric approach. The proposed quantum sensor consists of many surface-state electrons trapped individually on liquid helium by an electrode-network at the bottom of the liquid helium film. A dc-current in this chip is biased to generate a strong spin-orbit coupling of each of the trapped electrons. The mm wave signals are conducted to non-dissipatedly drive the orbital motions of the trapped electrons and result in the Stark shifts of the spin-orbit dressed states of the electrons. As a consequence, the electric fields of the conducted mm waves could be detected sensitively by using the Hahn echo interferometry with the long-lived spin states of the electrons trapped on liquid helium.

quant-ph↗

arXiv2024

Wide-range quantum enhanced rotation sensing with 1+2 dimensional dynamical decoupling techniques

We propose a motional dynamical decoupling technique by utilizing a sequence of $π$-phase shifts, instead of the conventional $π$-pulses for spin flipping, to implement the quantum enhanced rotation sensing with a 1+2 dimensional hybrid atomic Sagnic interferometor. By fully disentangling the spin from the two-dimensional vibrational modes of the particle under rotation, the spin coherence time and thus the phase accumulation can be significantly increased. Consequently, both the achievable sensitivity and dynamic range of the rotation sensing can be significantly enhanced and extended simultaneously, compared to the previous schemes where the spin and motions of the particle were not completely decoupled. The experimental feasibility for the unambiguous estimation of the rotation parameters is also discussed. Hopefully, this technique holds promise for overcoming certain challenges existing in the usual matter-wave Sagnac interferometers with trapped particles, particularly for the practical inertial navigation that demands both high sensitivity and large dynamic range.

quant-ph↗

arXiv2023

Sub-SQL electronic field sensing by simultaneously using quantum entanglements and squeezings

Quantum entanglement and quantum squeezing are two most typical approaches to beat the standard quantum limit (SQL) of the sensitive phase estimations in quantum metrology. Each of them has already been utilized individually to improve the sensitivity of electric field sensing with the trapped ion platform, but the upper bound of the demonstrated sensitivity gain is very limited, i.e., the experimental 3dB and theoretical 6dB, over the SQL. Here, by simultaneously using the internal (spin)-external (oscillator) state entanglements and the oscillator squeezings to effectively amplify the accumulation phase, we show that these sensitivity gains can be effectively surpassed. Hopefully, the proposal provides a novel approach to the stronger beaten of the SQL for the sensitive sensings of the desired electric field and also the other metrologies.

quant-ph↗

arXiv2023

Robust phase metrology with hybrid quantum interferometers against particle losses

Entanglement is an important quantum resource to achieve high sensitive quantum metrology. However, the rapid decoherence of quantum entangled states, due to the unavoidable environment noise, result in practically the unwanted sharp drop of the measurement sensitivity. To overcome such a difficulty, here we propose a spin-oscillator hybrid quantum interferometer to achieve the desirable precise estimation of the parameter encoded in the vibrations of the oscillator. Differing from the conventional two-mode quantum interferometers input by the two-mode NOON state or entangled coherent states (ECS), whose achievable sensitivities are strongly limited by the decoherence of the entangled vibrational states, we demonstrate that the present interferometer, input by a spin-dependent two-mode entangled state, possesses a manifest advantage, i.e., the measurement sensitivity of the estimated parameter is not influenced by the decoherence from the spin-oscillator entanglement. This is because that, by applying a spin-oscillator disentangled operation, the information of the estimated parameter encoded originally in the vibrational degrees can be effectively transferred into the spin degree and then can be sensitively estimated by the precise spin-state population measurements. As consequence, the proposed hybrid quantum interferometer possesses a manifest robustness against the particle losses of the vibrational modes. Interestingly, the achieved phase measurement sensitivity can still surpass the SQL obviously, even if relatively large number of particle loss occurs in one of the two modes. The potential application of the proposed spin-oscillator hybrid quantum interferometer is also discussed.

quant-ph↗