arXiv subjects

Kateryna Korshynska

Publications and source records attributed to Kateryna Korshynska.

3 recordsLinked to original sources

arXiv2025

Analytical description of collisional decoherence in a BEC double-well accelerometer

BEC-based quantum sensors offer a huge, yet not fully explored potential in gravimetry and ac- celerometry. In this paper, we study a possible setup for such a device, which is a weakly interacting Bose gas trapped in a double-well potential. In such a trap, the gas is known to exhibit Josephson oscillations, which rely on the coherence between the potential wells. Applying the density matrix approach, we consider transitions between the coherent, partially incoherent, and fully incoherent states of the Bose gas. We provide an analytical description of the collisional decoherence due to weak interactions, causing the Josephson oscillations to decay with time. In particular, we give the mathematical link between that decay in the density matrix approach and its interpretation in terms of phase fluctuations. To investigate the potential of the double-well setup as a quantum sensor we apply additional external acceleration to the system. The interplay of collisional interaction and ac- celeration leads to an additional shift of the oscillation frequency. We give the analytical expression for this shift and estimate the sensitivity of a hypothetical BEC double-well accelerometer based on that effect.

cond-mat.quant-gas↗

arXiv2024

Z' boson mass reach and model discrimination at muon colliders

We study the discrimination power of future multi-TeV muon colliders for a large set of models with extended gauge symmetries and additional neutral gauge bosons ("$Z'$-models"). Our study is carried out using a $χ^2$-analysis of leptonic observables of s-channel scattering in effective $Z'$-models. We make use of angular and chiral asymmetries induced in such models to find the discovery reach of a given muon collider setup in terms of the $Z'$ mass and to discriminate between the different scenarios. In this context, we discuss how polarized beams - should they become available at muon colliders - or polarization measurements can help in the discrimination. Our results show that typical muon collider setups which are currently under consideration can give a significantly higher reach compared to existing bounds and projections for high-luminosity LHC.

hep-ph↗

arXiv2024

Generalized Josephson effect in an asymmetric double-well potential at finite temperatures

We investigate a non-interacting many-particle bosonic system, placed in an asymmetric double-well potential. We first consider the dynamics of a single particle and determine its time-dependent probabilities to be in the left or the right well of the potential. These probabilities obey the standard Josephson equations, which in their many-particle interpretation also describe a globally coherent system, such as a Bose-Einstein condensate. This system exhibits the widely studied Josephson oscillations of the population imbalance between the wells. In our study we go beyond the regime of global coherence by developing a formalism based on an effective density matrix. This formalism gives rise to a generalization of Josephson equations, which differ from the standard ones by an additional parameter, that has the meaning of the degree of fragmentation. We first consider the solution of the generalized Josephson equations in the particular case of thermal equilibrium at finite temperatures, and extend our discussion to the non-equilibrium regime afterwards. Our model leads to a constraint on the maximum amplitude of Josephson oscillations for a given temperature and the total number of particles. A detailed analysis of this constraint for typical experimental scenarios is given.

quant-ph↗