Quantum Monte Carlo simulations confirm the existence of a bound state of a single He-3 atom at a free superfluid He-4 surface in three dimensions, localized within a ~10-A thick low-density He-4 surface layer, with a binding energy of approximately 4 K with respect to vacuum. As the temperature is raised above ~ 1 K the He-3 atom leaves the surface to dissolve into the superfluid. The situation is entirely different in two dimensions, as the He-3 atom is excluded from the superfluid and no surface bound state exists. Results are also presented for the a He-3 atom binding to nanoscale size He-4 clusters adsorbed on weak substrates, a physical system that may allow for the observation of some of the physics predicted for extended surfaces. It is shown that a He-3 bound state localized at the perimeter of sufficiently small (a few tens of atoms) clusters exists not just on Cs, as previously reported, but on all alkali substrates.Quantum Monte Carlo simulations confirm the existence of a bound state of a single He-3 atom at a free superfluid He-4 surface in three dimensions, localized within a ~10-A thick low-density He-4 surface layer, with a binding energy of approximately 4 K with respect to vacuum. As the temperature is raised above ~ 1 K the He-3 atom leaves the surface to dissolve into the superfluid. The situation is entirely different in two dimensions, as the He-3 atom is excluded from the superfluid and no surface bound state exists. Results are also presented for the a He-3 atom binding to nanoscale size He-4 clusters adsorbed on weak substrates, a physical system that may allow for the observation of some of the physics predicted for extended surfaces. It is shown that a He-3 bound state localized at the perimeter of sufficiently small (a few tens of atoms) clusters exists not just on Cs, as previously reported, but on all alkali substrates.

arXiv:2608.27664Aug 27, 20260 citations

Scattering and Bound States

Springer eBooksDec 12, 20050 citations

THE BOUND STATE REPRESENTATION

J Hamilton, Amira Salam

World Scientific series in 20th century physicsMay 1, 19940 citations

Self-bound droplets with uncorrelated disordered potentials

Karima Abbas, Abdelâali Boudjemâa

Abstract We investigate the effects of an external random δ -correlated potential on the bulk properties of self-bound droplets in three-dimensional binary Bose–Einstein condensates. The ground-state energy and the quantum fluctuation induced by disorder are computed utilizing the Bogoliubov theory. We provide a comprehensive stability phase-diagram for the resulting dirty droplets. At finite temperature, we calculate the free energy, and the thermal equilibrium density in terms of the disorder parameters. We show that the intriguing interplay of the thermal correction and the disorder may dissolve the droplet.Abstract We investigate the effects of an external random δ -correlated potential on the bulk properties of self-bound droplets in three-dimensional binary Bose–Einstein condensates. The ground-state energy and the quantum fluctuation induced by disorder are computed utilizing the Bogoliubov theory. We provide a comprehensive stability phase-diagram for the resulting dirty droplets. At finite temperature, we calculate the free energy, and the thermal equilibrium density in terms of the disorder parameters. We show that the intriguing interplay of the thermal correction and the disorder may dissolve the droplet.

Journal of Physics B Atomic Molecular and Optical PhysicsFeb 2, 20242 citations

The Decay of Coupled States

Princeton University Press eBooksApr 13, 20210 citations

How Quantum Is Bottomonium in the Quark-Gluon Plasma?

Nora Brambilla, Tom Magorsch

We study how much quantum structure bottomonium retains during its evolution in the quark-gluon plasma. Within the open quantum system framework, we simulate the Lindblad equation obtained from potential nonrelativistic QCD in the quantum Brownian regime. From the resulting real-time evolution of the bottomonium density matrix, we compute the Wigner transform and study its negativity as a measure of nonclassicality and a test of a key condition underlying classical Langevin-type approximations. We find that the medium suppresses the negativity, which nevertheless approaches a finite plateau close to that of the $1\mathrm{S}$ state. The overlaps with the excited $2\mathrm{S}$ and $3\mathrm{S}$ states arise from near-canceling positive and negative phase-space contributions, driven by negative regions in the Wigner transforms of the bound-state projectors, while the $1\mathrm{S}$ overlap is insensitive to such contributions. We further show that the position-space coherence is similarly suppressed and plateaus close to the 1S value. We trace the finite residual quantum structure to conditional purification: the medium preferentially dissolves weakly bound and unbound modes with large $\langle r^2\rangle$ , driving the surviving singlet $\mathrm{S}$ -wave ensemble toward the $1\mathrm{S}$ state. More broadly, these results reveal that classicalization is partial and observable dependent, a feature that is relevant across applications of open quantum system methods in fundamental physics.We study how much quantum structure bottomonium retains during its evolution in the quark-gluon plasma. Within the open quantum system framework, we simulate the Lindblad equation obtained from potential nonrelativistic QCD in the quantum Brownian regime. From the resulting real-time evolution of the bottomonium density matrix, we compute the Wigner transform and study its negativity as a measure of nonclassicality and a test of a key condition underlying classical Langevin-type approximations. We find that the medium suppresses the negativity, which nevertheless approaches a finite plateau close to that of the $1\mathrm{S}$ state. The overlaps with the excited $2\mathrm{S}$ and $3\mathrm{S}$ states arise from near-canceling positive and negative phase-space contributions, driven by negative regions in the Wigner transforms of the bound-state projectors, while the $1\mathrm{S}$ overlap is insensitive to such contributions. We further show that the position-space coherence is similarly suppressed and plateaus close to the 1S value. We trace the finite residual quantum structure to conditional purification: the medium preferentially dissolves weakly bound and unbound modes with large $\langle r^2\rangle$, driving the surviving singlet $\mathrm{S}$-wave ensemble toward the $1\mathrm{S}$ state. More broadly, these results reveal that classicalization is partial and observable dependent, a feature that is relevant across applications of open quantum system methods in fundamental physics.

hep-phCross-listedarXiv:2610.02313Oct 5, 20260 citations

1\mathrm{S}

state. The overlaps with the excited

2\mathrm{S}

and

3\mathrm{S}

states arise from near-canceling positive and negative phase-space contributions, driven by negative regions in the Wigner transforms of the bound-state projectors, while the

1\mathrm{S}

overlap is insensitive to such contributions. We further show that the position-space coherence is similarly suppressed and plateaus close to the 1S value. We trace the finite residual quantum structure to conditional purification: the medium preferentially dissolves weakly bound and unbound modes with large

\langle r^2\rangle

, driving the surviving singlet

\mathrm{S}

-wave ensemble toward the

1\mathrm{S}

state. More broadly, these results reveal that classicalization is partial and observable dependent, a feature that is relevant across applications of open quantum system methods in fundamental physics.