My current postdoctoral research at the Rochester Institute of Technology focuses on developing general theoretical frameworks for quantum devices and platforms, using atomic superfluids in optical cavities as a particularly clean and tunable testbed. Such systems enable coherent coupling between the long-lived collective excitations/persistent currents of Bose-Einstein condensates (BECs) and the quantum-optical fields of a cavity, thereby allowing controllable hybrid light-matter systems with cavity-enhanced strong coupling between the atomic modes and the optical field(s) that amalgamate superfluid and optomechanical behavior. A particular scenario that has generated recent interest is that of toroidally (ring)-trapped BECs in optical cavities where Laguerre-Gaussian beams imprint orbital angular momentum (OAM) onto the superfluid ring. The OAM-induced optical lattice leads to Bragg-diffracted atomic sidemodes that function as mechanical fluctuations hybridizing with the quantum optical field. From a theoretical standpoint, the resulting dynamics is formally equivalent to a broad class of cavity-optomechanical and circuit-QED systems, with atomic collective modes playing the role of effective mechanical or microwave degrees of freedom coupled to a driven cavity.
Specific projects:
1) Non-Hermitian Topological Sensing: Traditional approaches towards sensing superfluid rotation, i.e., the winding number L_p, relies on matter-wave interferometry and destructive measurements, an aspect theoretically shown very recently as bypassable. In the recent work [1], we have investigated a non-Hermitian optical dimer whose parameters are renormalized by dispersive and dissipative backaction from the coupling of the passive cavity with a ring-trapped BEC. Using an exact Schur-complement reduction of the full light-matter dynamics, we identified a static regime in which the atomic response produces a complex shift of the passive optical mode. This renormalized dimer supports a tunable exceptional point, enabling spectroscopic signatures in the optical transmission due to a probe field. Exploiting the topological charge, we have proposed a digital exceptional-point-based sensing scheme based on eigenmode permutation, providing a noise-resilient method to sense superfluid rotation without relying on eigenvalue splittings. The proposed sensing mechanism directly generalizes to other platforms, including optomechanical resonators and superconducting circuit architectures.
2) Atomic-Superfluid Quantum Heat Engines: In another recent work [2], we have proposed a quantum heat engine based on the Otto cycle. Since the cavity-enhanced light-atom coupling leads to the emergence of polaritonic modes whose character can be reversibly switched between photonlike and phononlike by detuning sweeps, this allows work extraction governed by distinct reservoirs. Beyond ideality, we have discussed finite-time scenarios based on shortcuts to adiabaticity such that the efficiency retains its ideal-operation value, despite finite-time challenges. Our analysis identifies OAM as an experimentally-accessible control knob that can reconfigure the performance of such quantum heat engines.Â
3) Quantum Memory for Twisted Light: In a recently-published project [3], we have theoretically proposed a photonic OAM quantum memory platform based on the same setup. In contrast to electromagnetically-induced-transparency-based protocols, our memory does not require change of internal atomic levels. The optical states are instead stored in the Hilbert space of topologically-protected and long-lived persistent currents of the condensate, yielding a storage time three orders of magnitude better than presently available. The use of a cavity provides orders of magnitude more resonances, and hence bandwidth, for reading and writing as compared to internal atomic transitions. This connects the language of cavity optomechanics to quantum-information storage with topologically-structured light.
Collaborators:
1) Mishkat Bhattacharya (RIT)
2) Nilamoni Daloi (RIT)
3) Himadri S. Dhar (IIT-B)
4) Pardeep Kumar (MPL)
5) Rahul Gupta (IIT-B)
Related publications:
[1] A. Ghosh, N. Daloi, and M. Bhattacharya, arXiv:2601.04749.
[2] A. Ghosh, N. Daloi, and M. Bhattacharya, arXiv:2510.19821.
[3] N. Daloi, R. Gupta, A. Ghosh, P. Kumar, H. S. Dhar, and M. Bhattacharya, Phys. Rev. Research 8, 013013 (2026) [arXiv].