New J. Phys. 16 053017 (2014)
http://dx.doi.org/10.1088/1367-2630/16/5/053017
We extend the concept of superadiabatic dynamics, or transitionless quantum driving, to quantum open systems whose evolution is governed by a master equation in the Lindblad form. We provide the general framework needed to determine the control strategy required to achieve superadiabaticity. We apply our formalism to two examples consisting of a two-level system coupled to environments with time-dependent bath operators.
Phys. Rev. Lett. 112, 201601 (2014)
http://dx.doi.org/10.1103/PhysRevLett.112.201601
We show that gauge invariant quantum link models, Abelian and non-Abelian, can be exactly described in terms of tensor networks states. Quantum link models represent an ideal bridge between high-energy and cold atom physics, as they can be used in cold atoms in optical lattices to study lattice gauge theories.
Phys. Rev. Lett. 113, 010502 (2014)
http://dx.doi.org/10.1103/PhysRevLett.113.010502
We study the relations between classical information and the feasibility of accurate manipulation of quantum system dynamics. We show that if an efficient classical representation of the dynamics exists, optimal control problems on many-body quantum systems can be solved efficiently with finite precision. In particular, one-dimensional slightly entangled dynamics can be efficiently controlled. We provide a bound for the minimal time necessary to perform the optimal process given the bandwidth of the control pulse, which is the continuous version of the Solovay-Kitaev theorem.
New J. Phys. 16, 093022 (2014)
http://dx.doi.org/10.1088/1367-2630/16/9/093022
New J. Phys. 16, 075007 (2014)
http://dx.doi.org/10.1088/1367-2630/16/7/075007
Phys. Rev. A 89, 042322 (2014)
http://dx.doi.org/10.1103/PhysRevA.89.042322
We demonstrate that arbitrary time evolutions of many-body quantum systems can be reversed even in cases when only part of the Hamiltonian can be controlled. The reversed dynamics obtained via optimal control—contrary to standard time-reversal procedures—is extremely robust to external sources of noise. We provide a lower bound on the control complexity of a many-body quantum dynamics in terms of the dimension of the manifold supporting it, elucidating the role played by integrability in this context.
Phys. Rev. B 89, 214408 (2014)
http://dx.doi.org/10.1103/PhysRevB.89.214408
We study the crossover from classical to quantum phase transitions at zero temperature within the framework of
Phys. Rev. Lett. 112, 250502 (2014)
http://dx.doi.org/10.1103/PhysRevLett.112.250502
We propose a simple idea for realizing a quantum gate with two fermions in a double well trap via external optical pulses without addressing the atoms individually. The key components of the scheme are Feshbach resonance and Pauli blocking, which decouple unwanted states from the dynamics. As a physical example we study atoms in the presence of a magnetic Feshbach resonance in a nanoplasmonic trap and discuss the constraints on the operation times for realistic parameters, reaching a fidelity above 99.9% within 42 μs, much shorter than existing atomic gate schemes.
New J. Phys. 16, 103015 (2014)
http://dx.doi.org/10.1088/1367-2630/16/10/103015
Nature Communications 5, 4009 (2014)
doi:10.1038/ncomms5009
The Ramsey interferometer is a prime example of precise control at the quantum level. It is usually implemented using internal states of atoms, molecules or ions, for which powerful manipulation procedures are now available. Whether it is possible to control external degrees of freedom of more complex, interacting many-body systems at this level remained an open question. Here we demonstrate a two-pulse Ramsey-type interferometer for non-classical motional states of a Bose–Einstein condensate in an anharmonic trap.