Quantum dissipation has been the object of study within the physics and chemistry communities for many years. Despite this, the field is in constant evolution, largely due to the fact that novel systems where the understanding of dissipation and dephasing processes is of crucial importance have become experimentally accessible in recent years. Among the ongoing research themes, we mention the defeat of decoherence in solid state-based quantum bits (qubits) (e.g. superconducting qubits or quantum dot based qubits), or dissipation due to non-equilibrium Fermi reservoirs, as is the case for quantum transport through meso- and nanoscale structures. A close inspection of dissipation in such systems reveals that one has to deal with 'unconventional' environments, where common assumptions of, for example, linearity of the bath and/or equilibrium reservoir have to be abandoned. Even for linear baths at equilibrium it might occur that the bath presents some internal structure, due, for example, to the presence of localized bath modes.

A large part of this focus issue is devoted to topics related to the rapidly developing fields of quantum computation and information with solid state nanodevices. In these implementations, single and two-qubit gates as well as quantum information transmission takes place in the presence of broadband noise that is typically non-Markovian and nonlinear. On both the experimental and theory side, understanding and defeating such noise sources has become a crucial step towards the implementation of efficient nanodevices.

On a more fundamental level, electron and spin transport through quantum dot nanostructures may suffer from 'unconventional' dissipation mechanisms such as the simultaneous presence of spin relaxation and fermionic dissipation, or may represent themselves out of equilibrium baths for nearby mesoscopic systems.

Finally, although not expected from the outset, the present collection of articles has revealed that different 'unconventional' questions were still open on the standard harmonic oscillator and spin baths. This includes both fundamental issues, such as the possibility of estimating the specific heat for a free particle in the presence of dissipation, and the development of methods suitable to dealing with long range correlations at zero temperature and with quantum chaotic environments.

We believe that the present focus issue on Quantum Dissipation in Unconventional Environments, although certainly not exhaustive, provides an important open-access resource that presents the latest state of the art of research in this field along its different lines.

Focus on Quantum Dissipation in Unconventional Environments Contents

Coherent control of an effective two-level system in a non-Markovian biomolecular environment
J Eckel, J H Reina and M Thorwart

Charge transfer dynamics in driven molecular ratchets: quantum Monte Carlo results and rate models
L Mühlbacher and J Ankerhold

Decoherence in qubits due to low-frequency noise
J Bergli, Y M Galperin and B L Altshuler

Dephasing by electron–electron interactions in a ballistic Mach–Zehnder interferometer
Clemens Neuenhahn and Florian Marquardt

Quantum frustration of dissipation by a spin bath
D D Bhaktavatsala Rao, Heiner Kohler and Fernando Sols

A random matrix theory of decoherence
T Gorin, C Pineda, H Kohler and T H Seligman

Dissipative dynamics of a biased qubit coupled to a harmonic oscillator: analytical results beyond the rotating wave approximation
Johannes Hausinger and Milena Grifoni

Dissipative dynamics of a two-level system resonantly coupled to a harmonic mode
Frederico Brito and Amir O Caldeira

Spin correlations in spin blockade
Rafael Sánchez, Sigmund Kohler and Gloria Platero

Landau–Zener tunnelling in dissipative circuit QED
David Zueco, Peter Hänggi and Sigmund Kohler

Quantum oscillations in the spin-boson model: reduced visibility from non-Markovian effects and initial entanglement
F K Wilhelm

Dynamics of dissipative coupled spins: decoherence, relaxation and effects of a spin-boson bath
P Nägele, G Campagnano and U Weiss

Spin chain model for correlated quantum channels
Davide Rossini, Vittorio Giovannetti and Simone Montangero

Finite quantum dissipation: the challenge of obtaining specific heat
Peter Hänggi, Gert-Ludwig Ingold and Peter Talkner

Dynamics of large anisotropic spin in a sub-ohmic dissipative environment close to a quantum-phase transition
Frithjof B Anders

Effects of low-frequency noise cross-correlations in coupled superconducting qubits
A D'Arrigo, A Mastellone, E Paladino and G Falci

From coherent motion to localization: dynamics of the spin-boson model at zero temperature
Haobin Wang and Michael Thoss

Phonon distributions of a single-bath mode coupled to a quantum dot
F Cavaliere, G Piovano, E Paladino and M Sassetti