Biomedical subjects

Philippe Jacquod

Publications and source records attributed to Philippe Jacquod.

3 recordsLinked to original sources

PubMed2005

Chaos, coherence, and the double-slit experiment.

We investigate the influence that classical dynamics has on interference patterns in coherence experiments. We calculate the time-integrated probability current through an absorbing screen and the conductance through a doubly connected ballistic cavity, both in an Aharonov-Bohm geometry with forward scattering only. We show how interference fringes in the probability current generically disappear in the case of a chaotic system with small openings, and how they may persist in the case of an integrable cavity. Simultaneously, the typical, sample dependent amplitude of the flux-sensitive g(phi) part of the conductance survives in all cases, and becomes universal in the case of a chaotic cavity. In the presence of dephasing by fluctuations of the electric potential in one arm of the Aharonov-Bohm loop, we find an exponential damping of the flux-dependent part of the conductance, g(phi) proportional exp[-tauL/tauphi, in term of the traversal time tauL through the arm and the dephasing time tauphi. This extends previous works on dephasing in ballistic systems to the case of many conducting channels.

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PubMed2005

Mesoscopic fluctuations of the Loschmidt echo.

We investigate the time-dependent variance of the fidelity with which an initial narrow wave packet is reconstructed after its dynamics is time reversed with a perturbed Hamiltonian. In the semiclassical regime of perturbation, we show that the variance first rises algebraically up to a critical time t(c) , after which it decays. To leading order in the effective Planck's constant Planck's(eff) , this decay is given by the sum of a classical term approximately same as exp [-2lambdat] , a quantum term approximately same as 2Planck's(eff) exp [-Gamma t] , and a mixed term approximately 2 exp [- (Gamma+lambda) t] . Compared to the behavior of the average fidelity, this allows for the extraction of the classical Lyapunov exponent lambda in a larger parameter range. Our results are confirmed by numerical simulations.

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PubMed2002

Duality between the weak and strong interaction limits for randomly interacting fermions.

We establish the existence of a duality transformation for generic models of interacting fermions with two-body interactions. The eigenstates at weak and strong interaction U possess similar statistical properties when expressed in the U=0 and U= infinity eigenstates bases, respectively. This implies the existence of a duality point U(d) where the eigenstates have the same spreading in both bases. U(d) is surrounded by an interval of finite width which is characterized by a non-Lorentzian spreading of the strength function in both bases. Scaling arguments predict the survival of this intermediate regime as the number of particles is increased.

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