Category Harvard University

Entries 2 Total

Quantum fragile matter: mechanical excitations of a Reggeon ion chain

Feb 22, ’13 9:56 AM

Philipp Strack, Vincenzo Vitelli

This paper proposes to study quantum fragile materials with small linear elasticity and a strong response to zero-point fluctuations. As a first model, we consider a non-unitary (but PT-symmetric) massive quantum chain with a Reggeon-type cubic nonlinearity. At the critical point, the chain supports neither the ordinary quantum phonons of a Luttinger liquid, nor the supersonic solitons that arise in classical fragile critical points in the absence of fluctuations. Quantum fluctuations, approximately captured within a one-loop renormalization group, give rise to mechanical excitations with a nonlinear dispersion relation and dissipative spectral behavior. Models of similar complexity should be realizable with trapped ions.

http://arxiv.org/abs/1302.4453
Quantum Gases (cond-mat.quant-gas); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics – Theory (hep-th); Quantum Physics (quant-ph)

Comments (0)

A third-order exceptional point e ect on the dynamics of a single particle in a time-dependent harmonic trap

Dec 14, ’12 12:39 PM

Raam Uzdin, Emanuele Dalla Torre, Ronnie Kosloff, Nimrod Moiseyev

The time evolution of a single particle in a harmonic trap with time dependent frequency omega(t) is well studied. Nevertheless here we show that, when the harmonic trap is opened (or closed) as function of time while keeping the adiabatic parameter mu = [d omega(t)/dt]/omega(t)^2 fixed, a sharp transition from an oscillatory to a monotonic exponential dynamics occurs at mu = 2. At this transition point the time evolution has a third-order exceptional point (EP) at all instants. This situation, where an EP of a time-dependent Hermitian Hamiltonian is obtained at any given time, is very different from other known cases. Our finding is relevant to the dynamics of a single ion in a magnetic, optical, or rf trap, and of diluted gases of ultracold atoms in optical traps.

http://arxiv.org/abs/1212.3077
Quantum Physics (quant-ph); Quantum Gases (cond-mat.quant-gas)

Comments (0)