Hot Topics in Quantum Statistical Physics:

q-Thermodynamics, q-Decoherence and q-Motors

August 11 – 16, 2003

The workshop brought together a number of leading scientists and junior researchers working in the fields of quantum Brownian systems and quantum limits of the second law. The intent of the workshop was to discuss hot topics in these fields, fostering discussions, envisaging future directions and establishing collaborations and connections. The general and actual interest in these issues has been confirmed by the high number of participants (53) who attended the workshop and the stimulating atmosphere thus created.

The subjects discussed were:

· Quantum limits to the second law;

· Quantum decoherence and quantum measurement;

· Quantum motors.

The discussion related to the "Quantum Limits to the Second Law" is a rapidly growing subject. Quantum Brownian motors represent a challenge both on the theoretical and on the experimental side. Issues related to quantum coherence and the measurement process have a tremendous impact in new emerging fields, as e.g. in quantum information processing or in coherence phenomena in low-dimensional systems. The workshop focused on the quantum statistical aspects of these phenomena, together with possible applications.

The format of the workshop consisted in dedicated topic sections, on q-motors, q-thermodynamics, q-computing, q-coherence and q-dissipation (four talks in the morning and on the average two talks in the afternoon, leaving free time for discussions).

Moreover a special symposium day on "Quantum Dissipation" has taken place on Wednesday 13 of August, in honor of Prof. Ulrich Weiss (Stuttgart). This symposium has attracted a number of scientists, 52 registered plus many participants working in Leiden University and TU Delft University who attended the symposium.

Highlights:

The diversity of the issues covered is simply elucidated by the following synopsis of the invited and contributing talks.

Quantum Brownian motors:

Peter Hänggi, Brownian motors in physics and biology, Stefan Scheidl, Brownian motion in ratchet potentials, Tomas Novotny, Quantum theory of shuttling instability, Ken Segall, Fluxon ratchet dynamics in a 1-D circular array of Josephson Junctions, Joël Peguiron, Few-bands quantum ratchets, Tammy Humphrey, Quantum heat engines in the maximum power regime.

Quantum Thermodynamics:

Markus Buttiker, Ground state energy fluctuations and entanglement for a system coupled to a bath; Marlan Scully, Radiative quantum thermodynamics, including a solid state version of the Unruh effect; Armen Allahverdyan, Optimal but non-thermodynamic and non-adiabatic work extraction from mesoscopic systems.

Symposium on Quantum Dissipation:

Amir Caldeira Quantum dissipation and applications, Hans Mooij Superconducting flux qubits, David Haviland Quantum fluctuation effects in 1D Josephson junction arrays, Paolo Tombesi Actively controlling decoherence in quantum systems, Gert-Ludwig Ingold Overdamped Josephson junction and duality: Between Coulomb blockade and macroscopic quantum tunnelling, Giuseppe Falci Modulation of dephasing due to a spin-boson environment, Peter Talkner, Is the dynamics of an open quantum system always linear?, Reinhold Egger Dissipative quantum dynamics simulations, Jürgen Stockburger Stochastic Liouville-von Neuman equations for non-Markovian quantum dissipation decoherence and transport.

Special event: evening colloquium of Dr Prof Herman Grabert on Macroscopic quantum tunneling in Josephson systems.

Quantum Computation:

Denis Vion, Steering the quantum state of an electrical circuit, Irinel Chiorescu Quantum decoherence for a superconducting flux qubit, Kouichi Semba Single shot readout of the flux qubit, Alexander Shnirman Noise and decoherence in quantum two-state systems: nonlinear coupling and higher-order effects, Michael Thorwart Dephasing and relaxation in a flux qubit coupled to a noisy detector, Frank Wilhelm Engineering decoherence of solid state quantum bits.

Quantum Dissipation:

Ulrich Weiss, Nonequilibrium quantum decay, decoherence and noise in quantum impurity problems, Fernando Sols Quantum electrodynamical fluctuations in the macroscopic phase of a Josephson link, Robert Withney, Berry phase of non-orthogonal resonances, Massimo Palma Berry phase for a spin ½ in a classical fluctuating field, Jens Siewert Tunneling rates for ferromagnetic junctions.

Many young researchers were present at the workshop and had the opportunity to present their work in a poster session.

The response of the participants was extremely positive, and many agitated discussions took place during and after the lectures. Scully lost a scientific bet with Hanggi and Talkner, but nevertheless claimed victory. Besides the interest in the scientific program, the participants have appreciated the facilities offered by the Lorentz center, the well-equipped offices, computer services and the excellent professional support by the local program assistant Gerda Filippo, and the executive manager Dr Martje Kruk-de Bruin.

Finally Prof. Wim van Saarloos’s generous and efficient help has been highly appreciated by the scientific organizers.

T.M. Nieuwenhuizen (ITF, UvA,, The Netherlands)

M. Grifoni (University Delft, The Netherlands)

E. Paladino (Catania University, Italy)