arXiv subjects

Rongchun Ge

Publications and source records attributed to Rongchun Ge.

8 recordsLinked to original sources

arXiv2026

Dynamics of entanglement in non-Hermitian system of nonreciprocal coupling

The exploration of the effect of non-Hermitian (NH) in quantum systems is gaining renewed momentum as a result of the recent progress in experiments. It has been indicated that the ability to engineer the orders of exceptional points (EPs) can be fundamental to its applications in quantum control, such as accelerating entanglement generation; however, an initial survey of the interactions between different orders of EPs is still missing. In this work, we try to partially address this issue by employing a non-reciprocally coupled cavity system which can be experimentally realizable with a two-dimensional reconfigurable NH gauged laser array. With deliberate design, our systems display both second and third orders of EPs. The sign of a novel, purely quantum continuous entanglement phase transition is observed, which reveals how multi-EP interactions alter entanglement dynamics across different regimes while maintaining accelerated generation. Our findings reveil the genuinely quantum NH physics of higher-order EPs, which has opened up a new avenue for future investigations of the higher-order degeneracy application and the dynamic phase transitions of quantum systems.

quant-ph↗

arXiv2025

Single-Light-Pulse Driven Compact Atom Interferometry with Measurement Induced Large Momentum Transfer

We propose a fundamentally new design strategy of light-pulsed atom interferometry (LPAI) with a single atomic beam splitter. A traditional $\pi/2$-pulse Raman beam is employed to render a small momentum transfer at the initial state. After a short period of evolution during which physical relevant information can be loaded, a quantum weak measurement is applied to the internal state of the atoms. The final information will be detected from the transmission spectrum of a probe light to obviate the measurement of florescence signal. An effective amplification of the order of $10^3$ about the momentum offset is achieved in our simulation employing $Cs$ atoms with current experimental condition. Our proposal offers a cost-effective, high-accuracy measurement and readout strategy for LPAI. Furthermore, the strategy makes the physical setup much simpler and more compact offering new direction towards portable sensitive LPAI.

quant-ph↗

arXiv2024

Weak-measurement-based pseudospin pointer: A cost-effective scheme for precision measurement

As an essential component of state-of-the-art quantum technologies, fast and efficient quantum measurements are in persistent demand over time. We present a proof-of-principle experiment on a new dimensionless pseudo-spin pointer based on weak measurement. In the context of optical parameter estimation, we demonstrate that the parametric distribution's moment is obtained experimentally by employing the dimensionless pointer without measuring the distribution literally. In addition to the sheer liberation of experimental expense, the photon-countering-based pointer is well-calibrated for the detection of weak signals. We show that for signals $3$-$4$ orders of weaker in strength than the area-array camera method, an order of improvement in precision is achieved experimentally.

quant-ph↗

arXiv2023

Meta-lenses for differential imaging based on weak measurement

All-optical information communication, processing and computation have received substantial interest of both fundamental and applied research due to its unrivaled speed and broad bandwidth. Compared to its electronic counterpart, photons seldom interact with each other which makes them obtain a long coherence time on one hand and relieved from heavy energy dissipation on the other. However, one of the hindrances to achieve all-optical circuits is the large volume of all-optical devices to achieve specific functionalities. In this work, we propose and demonstrate experimentally three meta-lenses for differential imaging employing the framework of weak measurement: (1) partial differential lens, (2) total differential lens and (3) second order differential lens compatible with the requirement of miniaturization to achieve all-optical technology. Based on Fresnel-lens-like structures, our meta-lenses incorporated the previous weak-measurement compartment into wavelength scale, which induces a miniature differential operation system as a result. In addition to its potential importance in heavily integrated all-optical neural networks, the differential lens can be easily incorporated in the existing imaging systems like a conventional lens without increasing the complexity of the system of interest.

physics.optics↗

arXiv2022

A general scheme of differential imaging employing weak measurement

We propose and experimentally realize a general scheme of differential imaging employing the idea of weak measurement. We show that the weak coupling between the system of interest and a two-level ancilla can introduce a two-beam circuit after an arbitrary pre-selection of the ancilla. By choosing the post-selection orthogonal to the pre-selection measurement, an effective imaging platform based on differential operations is shown achieved. Experimental results on both the Sagnac interferometer and ultra-thin Wollaston prism demonstrate that our imaging scheme successfully yields the boundary information of complex geometric configurations.

physics.optics↗

arXiv2021

Quasiperiodic Floquet-Thouless energy pump

Recent work [M. H. Kolodrubetz et al, PRL 120, 150601] has demonstrated that periodically driven one-dimensional fermionic systems can support quantized energy pumping resulting from an adiabatic modulation of a second parameter. In this work, we explore this topological Floquet-Thouless energy pump in the quasiperiodic driving regime where the parametric driving occurs at finite frequency. We show that quantization of energy pumping persists for finite ramping frequencies, as long as they are incommensurate with the driving frequency, and the system remains localized by spatial disorder. Thus, the topological Floquet-Thouless energy pump is stable beyond the adiabatic regime, occupying a finite region of parameter space. Phase transitions away from these topological phases are accompanied by delocalization in position space, photon number (energy) space, or both. Using a dimensional reduction scheme, we demonstrate that a related phase can be realized with a cavity-qubit system driven by two incommensurate modes.

cond-mat.mes-hall↗

arXiv2021

Floquet engineering flat bands for bosonic fractional quantum Hall in small lattices

The quest to realize novel phases of matter with topological order is an important pursuit with implications for strongly correlated physics and quantum information. Utilizing ideas from state-of-the-art coherent control of artificial quantum systems such as superconducting circuits, we present a proposal to realize bosonic fractional quantum Hall physics on small lattices by creating nearly flat topological bands using staggered flux patterns. Fingerprints of fractionalization through charge pumping can be observed with nearly perfect quantization using as few as 24 lattice sites (two photons). We suggest an implementation using a finite lattice of superconducting qubits with cylindrical connectivity on both triangular and square lattices.

cond-mat.mes-hall↗

arXiv2018

Floquet Topological Polaritons in Semiconductor Microcavities

We propose and model Floquet topological polaritons in semiconductor microcavities, using the interference of frequency detuned coherent fields to provide a time periodic potential. For arbitrarily weak field strength, where the Floquet frequency is larger than the relevant bandwidth of the system, a Chern insulator is obtained. As the field strength is increased, a topological phase transition is observed with an unpaired Dirac cone proclaiming the anomalous Floquet topological insulator. As the relevant bandwidth increases even further, an exotic Chern insulator with flat band is observed with unpaired Dirac cone at the second critical point. Considering the polariton spin degree of freedom, we find that the choice of field polarization allows oppositely polarized polaritons to either co-propagate or counter-propagate in chiral edge states.

cond-mat.mes-hall↗