arXiv subjects

Jugal Talukdar

Publications and source records attributed to Jugal Talukdar.

3 recordsLinked to original sources

arXiv2025

Tunable Non-Gaussian Mechanical States in a Strongly Coupled Hybrid Quantum System

Quantum states of motion are critical components in the second quantum revolution. We investigate the generation and control of non-Gaussian motional states in a tripartite hybrid quantum system consisting of a collection of qubits coupled to a mechanical resonator, which in turn interacts with an externally driven photonic cavity. This hybrid architecture provides a versatile platform for quantum control by integrating nonlinear interactions and multiple control parameters. Operating in the strong coupling regime, we study the transient dynamics resulting from a time-dependent external drive that has a boxcar profile. Starting from coherent states in both the mechanical and cavity subsystems, we show that this drive protocol, combined with time-independent interaction and frequency configurations, leads to the emergence of highly non-Gaussian quantum states in the intermediary mechanical degree of freedom. These states are characterized by a pronounced negative volume in the Wigner quasi-probability distribution and enhanced quantum Fisher information, indicative of their quantum utility. We systematically analyze the impact of the qubit phase, interaction strengths, and drive parameters on the degree of non-Gaussianity. Our findings underscore the tunability and richness of this hybrid platform, paving the way for advanced quantum state engineering and applications in quantum sensing, metrology, and information processing.

quant-ph↗

arXiv2024

Efficient Multiparty Entanglement Distribution in Dynamic Quantum Networks

Distributing multipartite entanglement over a quantum network means routing it through a shared resource state. Existing measurement-based schemes search for a fresh path and re-verify the topology before every request, placing a network-wide classical exchange on the critical path of each one. We introduce DODAG-X, which removes it. A single destination-oriented directed acyclic graph spanning tree is computed once and reused across all requests, so each party's route is recovered by following parent pointers instead of by a new search. The per-request routing cost drops from $\mathcal{O}(N)$ to $\mathcal{O}(\sqrt{N})$ on symmetric grids and to $\mathcal{O}(\log N)$ on small-world networks for $N$ nodes, and only the $N-1$ tree links need be maintained under link loss. Routing on the sparse tree also shrinks the neighborhoods cleared to isolate the parties, lowering measurements per request by roughly 19\% on small-world graphs and up to 34\% on moderately dense, strongly rewired ones; on a fixed tree the two protocols use identical counts. We prove correctness for up to three parties with no restriction on topology, and prove a sufficient condition under which one application yields an $n$-party GHZ state for any $n$. We then delimit it, exhibiting requests outside the hypothesis whose output is multipartite entangled yet in a different local-Clifford class. Under a discrete-time Markov failure model the classical repair layer matches the reachability of full-graph re-search up to a failed-edge fraction of one half, and a coherence criterion relating tree depth to memory lifetime identifies the viable hardware platforms.

quant-ph↗

arXiv2020

Dynamics of Rydberg excitations and quantum correlations in an atomic array coupled to a photonic crystal waveguide

We study the dynamics of up to two Rydberg excitations and the correlation growth in a chain of atoms coupled to a photonic crystal waveguide. In this setup, an excitation can hop from one atom to another via exponentially decaying exchange interactions mediated by the waveguide. An initially localized excitation undergoes a continuous-time quantum walk for short-range hopping, and for long-range, it experiences quasi-localization. Besides that, the inverse participation ratio reveals a super-ballistic diffusion of the excitation in short times, whereas, at a long time, it becomes ballistic. For two initially localized excitations, intriguing, and complex dynamical scenarios emerge for different initial separations due to the competition between the Rydberg-Rydberg and exchange interactions. In particular, the two-point correlation reveals a light-cone behavior even for sufficiently long-range exchange interactions. Additionally, we characterize the growth of bipartite entanglement entropy, which exhibits a global bound if only one excitation is present in the dynamics. Finally, we analyze the effect of imperfections due to spontaneous emission from the Rydberg state into photons outside the waveguide and show that all physical phenomena we predict are well within experimental reach.

cond-mat.quant-gas↗