arXiv subjects

E. Gvozdiovas

Publications and source records attributed to E. Gvozdiovas.

3 recordsLinked to original sources

arXiv2026

Quantum transport in a non-Hermitian 1D synthetic lattice: from quantum Zeno reflection to near-perfect absorption

We experimentally explore the absorption of a propagating wavepacket impinging upon a dissipative region in an engineered quantum system. We employ a 1D non-Hermitian synthetic lattice with an abrupt interface between dissipative and non-dissipative subchains, using the states of the electronic ground-state hyperfine manifold in a $^{87}$Rb Bose-Einstein condensate as sites. By tuning the dissipation rate, we observe a progression from ballistic propagation, to near-perfect absorption, to quantum Zeno reflection. Guided by numerical simulations, we identify that optimal absorption occurs when tunneling and dissipation are properly matched, and find qualitative agreement with an idealized semi-infinite model across all dissipation regimes. Our results establish synthetic lattices as a versatile Quantum simulation platform for dissipation-engineered quantum transport and highlight controlled dissipation as a resource for tailoring quantum dynamics.

cond-mat.quant-gas↗

arXiv2026

In situ magnetic-field stabilization for quantum-gas experiments

We demonstrate a minimally-destructive in situ technique for measuring and stabilizing slowly-drifting magnetic fields in ultracold-atom experiments. While conventional magnetic-field sensors such as Hall, giant magnetoresistive, or fluxgate-based devices are broadly used, their accuracy, precision and dynamic range can be limited. In addition, these sensors are typically positioned at least several centimeters away from the in-vacuum atomic system, as their operation creates perturbing magnetic fields, and their placement is limited by geometric constraints imposed by the vacuum system. We overcome these issues by using the atomic system itself as a built-in magnetometer. To that end, we employ a pair of weak measurements to determine the Zeeman splitting -- and thereby the magnetic field -- of a magnetically sensitive atomic transition. We provide closed-form expressions quantifying the trade-offs between measurement noise, dynamic range, and atom loss. This procedure is demonstrated with ultracold Rb-87, weakly measured using partial-transfer absorption imaging. We then incorporate a Kalman filter to stabilize the magnetic field; this eliminated long-term drift in the ambient field (as high as ~70 nT/hr) in exchange for a modest increase in shot-to-shot variability from 1.8(2) nT to 2.0(2) nT.

physics.atom-ph↗

arXiv2021

Optical lattice with spin-dependent sub-wavelength barriers

We analyze a tripod atom light coupling scheme characterized by two dark states playing the role of quasi-spin states. It is demonstrated that by properly configuring the coupling laser fields, one can create a lattice with spin-dependent sub-wavelength barriers. This allows to flexibly alter the atomic motion ranging from atomic dynamics in the effective brick-wall type lattice to free motion of atoms in one dark state and a tight binding lattice with a twice smaller periodicity for atoms in the other dark state. Between the two regimes, the spectrum undergoes significant changes controlled by the laser fields. The tripod lattice can be produced using current experimental techniques. The use of the tripod scheme to create a lattice of degenerate dark states opens new possibilities for spin ordering and symmetry breaking.

quant-ph↗