ELFT HÍRADÓ

[Janos Asboth <asboth.janos AT ttk.bme.hu>]

Meghívó

BME Elméleti Fizika Szeminárium,

szept. 30. péntek 10h15,

1111 Budapest, Budafoki út 8., BME F III. magasföldszint 01.,
Elméleti Fizika Tanszék szemináriumi szoba

Grabarits András (BME Elméleti Fizika Tanszék):
Superdiffusive quantum work and adiabatic quantum evolution in finite
temperature chaotic Fermi systems

Even though the change of energy and the related concepts of heat and work
are fundamental quantities in thermodynamics, their understanding in the
context of quantum systems is still incomplete. Here, 'work' W is commonly
defined as energy transfer during some deformation of the system. It
requires a two-time measurement scheme, in which the energy E of the time
evolved system is measured at time t=0, and at a later time t. Work is
thus a statistical quantity due to thermal and quantum fluctuations.

We study[1] the full distribution of quantum work in generic,
noninteracting, disordered fermionic nanosystems at finite temperature. In
particular, we consider disordered zero-dimensional quantum dots described
by Random Matrix Theory in which we derive an analytical determinant
formula for the characteristic function of work statistics for quantum
quenches starting from a thermal initial state. For work small compared to
the thermal energy of the Fermi gas, work distribution is Gaussian, and the
variance of work is proportional to the average work, while in the
low-temperature or large-work limit, a non-Gaussian distribution with
superdiffusive work fluctuations is observed. Similarly, the time
dependence of the probability of adiabaticity crosses over from an
exponential to a stretched exponential behavior. For large enough average
work, the work distribution becomes universal, and depends only on the
temperature and the mean work. Apart from initial low-temperature
transients, work statistics are well captured by a Markovian energy-space
diffusion process of hardcore particles, starting from a thermal initial
state. Our findings can be verified by measurements on nanoscale circuits
or via single qubit interferometry

[1]: A Grabarits, M Kormos, I Lovas, and G Zaránd, Phys. Rev. B 106, 064201
(2022)


Minden érdeklődőt szeretettel várunk.
Asbóth János,
 szemináriumi koordinátor