arXiv subjects

J. S. You

Publications and source records attributed to J. S. You.

3 recordsLinked to original sources

arXiv2024

A Theoretical Study of Cavity-modulated Topological Anderson Insulators

Strong light-matter interaction has been demonstrated feasible for controlling phases of matter. In this work, the interplay with disorder is studied and rich phenomena are demonstrated. Specifically, the topological phases of the disordered longer-range Su-Schrieffer-Heeger (SSH) model coupled with cavity photons are studied numerically. It is found that cavity photons modify the hopping amplitudes, resulting in the change of phase transition boundaries, and disorder induced topological Anderson insulating (TAI) phases even in the presence of cavity photons. The critical disorder strength at the phase transitions, determined by localization lengths, can be modulated by cavity photons through the modified hopping amplitudes. Our work extends the study of cavity-coupled solid state systems to disordered lattices.

cond-mat.mtrl-sci↗

arXiv2024

Robustness of tripartite entangled states in passive PT-symmetric qubits

Non-Hermitian quantum systems have attracted significant interest in recent years due to the presence of unique spectral singularities known as exceptional points (EPs), where eigenvalues and eigenvectors coalesce. The drastic changes in these systems around their EPs have led to unique entanglement dynamics, which remained elusive until quite recently. In this work, we theoretically investigate the robustness of tripartite entanglement induced by EPs of the passive PT-symmetric non-Hermitian superconducting qubits, both in stand-alone configurations and hybrid setups with Hermitian qubits. In particular, we consider the qubits with both all-to-all and nearest-neighbour couplings under uniform and non-uniform coupling strengths. Our results reveal that non-Hermitian qubits with all-to-all coupling generate GHZ states, while those with nearest-neighbour interactions produce W states. These entangled states are resilient to non-uniform couplings and off-resonant driving fields. Moreover, the hybrid configurations combining Hermitian and non-Hermitian qubits suggest the importance of EPs for generating and maintaining genuine tripartite entanglement in our system. Additionally, driving the PT-symmetric qubits with a strong Rabi frequency can help sustain tripartite entanglement over time by countering losses, while strong inter-qubit coupling can benefit these entangled states in the low dissipation regime. These findings suggest that exploiting non-Hermitian systems and their associated EPs can create robust entangled states which are useful for both fundamental studies and quantum technologies.

quant-ph↗

arXiv2024

Accelerating multipartite entanglement generation in non-Hermitian superconducting qubits

Open quantum systems are susceptible to losses in information, energy, and particles due to their surrounding environment. One novel strategy to mitigate these losses is to transform them into advantages for quantum technologies through tailored non-Hermitian quantum systems. In this work, we theoretically propose a fast generation of multipartite entanglement in non-Hermitian qubits. Our findings reveal that weakly coupled non-Hermitian qubits can accelerate multiparty entanglement generation by thousands of times compared to Hermitian qubits, in particular when approaching the $2^n$-th order exceptional points of $n$ qubits in the ${\cal P}{\cal T}-$ symmetric regime. Furthermore, we show that Hermitian qubits can generate GHZ states with a high fidelity more than $0.9995$ in a timescale comparable to that of non-Hermitian qubits, but at the expense of intense driving and large coupling constant. Our approach is scalable to a large number of qubits, presenting a promising pathway for advancing quantum technologies through the non-Hermiticity and higher-order exceptional points in many-body quantum systems.

quant-ph↗