16.10.Jn Josephson nanodevices

Optimizing for an arbitrary perfect entangler. II. Application

Date: 
2015-06-08
Author(s): 

M. H. Goerz, G. Gualdi, D. M. Reich, C. P. Koch, F. x Motzoi, K. B. Whaley, J. Vala, M. M. Müller, S. Montangero, T. Calarco

Reference: 

Phys. Rev. A 91, 062307 (2015)
http://dx.doi.org/10.1103/PhysRevA.91.062307

The difficulty of an optimization task in quantum information science depends on the proper mathematical expression of the physical target. Here we demonstrate the power of optimization functionals targeting an arbitrary perfect two-qubit entangler, which allow generation of a maximally entangled state from some initial product state.

Quantum speed limit and optimal control of many-boson dynamics

Date: 
2015-12-07
Author(s): 

I. Brouzos, A. I. Streltsov, A. Negretti, R. S. Said, T. Caneva, S. Montangero, T. Calarco

Reference: 

Phys. Rev. A 92, 062110 (2015)
http://dx.doi.org/10.1103/PhysRevA.92.062110

We apply the concept of quantum speed limit (QSL)—the minimal time needed to perform a driven evolution—to complex interacting many-body systems where the effects of interactions have to be taken into account. We introduce a general strategy to eliminate the detrimental effects of the interparticle repulsion and drive the system at the QSL by applying a compensating control pulse (CCP).

Parity dependent Josephson current through a helical Luttinger liquid

Date: 
2013-08-23
Author(s): 

S Barbarino, R Fazio, M Sassetti, F Taddei

Reference: 

New J. Phys. 15 (2013) 085025

Bosonic Josephson Junction Controlled by a Single Trapped Ion

Date: 
2012-08-22
Author(s): 

R. Gerritsma, A. Negretti, H. Deork, Z. Idziaszek, T. Calarco, F. Schmidt-Kaler

Reference: 

URL: http://link.aps.org/doi/10.1103/PhysRevLett.109.080402
DOI: 10.1103/PhysRevLett.109.080402
PACS: 03.75.Gg, 03.75.Lm, 34.50.Cx, 37.10.Ty

We theoretically investigate the properties of a double-well bosonic Josephson junction coupled to a single trapped ion.

Bosonic Josephson Junction Controlled by a Single Trapped Ion

Date: 
2012-08-22
Author(s): 

R. Gerritsma, A. Negretti, H. Doerk, Z. Idziaszek, T. Calarco, and F. Schmidt-Kaler

Reference: 

Phys. Rev. Lett. 109, 080402 (2012)

We theoretically investigate the properties of a double-well bosonic Josephson junction coupled to a single trapped ion. We find that the coupling between the wells can be controlled by the internal state of the ion, which can be used for studying mesoscopic entanglement between the two systems and to measure their interaction with high precision. As a particular example we consider a single 87Rb atom and a small Bose-Einstein condensate controlled by a single 171Yb+ ion.

Detecting phonon blockade with photons

Date: 
2011-08-04
Author(s): 

N. Didier, S. Pugnetti, Y. M. Blanter, and R. Fazio

Reference: 

Phys. Rev. B 84, 054503 (2011)

Measuring the quantum dynamics of a mechanical system, when few phonons are involved, remains a challenge. We show that a superconducting microwave resonator linearly coupled to the mechanical mode constitutes a very powerful probe for this scope. This new coupling can be much stronger than the usual radiation pressure interaction by adjusting a gate voltage. We focus on the detection of phonon blockade, showing that it can be observed by measuring the statistics of the light in the cavity. The underlying reason is the formation of an entangled state between the two resonators.

Two-Point Phase Correlations of a One-Dimensional Bosonic Josephson Junction

Date: 
2011-01-14
Author(s): 

T. Betz, S. Manz, R. Bücher, T. Berrada, Ch. Koller, G. Kazakov, I.E. Mazets, H.-P. Stimming, A. Perrin, T. Schumm, J. Schmiedmayer

Reference: 

Phys. Rev. Lett. 106 020407 (2011)

Nonadiabatic Josephson dynamics in junctions with in-gap quasiparticles

Date: 
2010-10-01
Author(s): 

J. Michelsen and V. S. Shumeiko

Reference: 

Low Temp. Phys. 36, 925 (2010)

Trapped electron coupled to superconducting devices

Date: 
2010-09-17
Author(s): 

P. Bushev, D. Bothner, J. Nagel. M. Kemmelr, K.B. Konovalenko, A. Loerincz, K. Ilin, M. Siegel, D. Koelle, R. Kleiner, F. Schmidt-Kaler

Reference: 

Eur. Phys. J. D 63, 9-16 (2011)

We propose to couple a trapped single electron to superconducting structures located at a variable distance from the electron. The electron is captured in a cryogenic Penning trap using electric fields and a static magnetic field in the Tesla range. Measurements on the electron will allow investigating the properties of the superconductor such as vortex structure, damping and decoherence.

Decoherence in Adiabatic Quantum Evolution: Application to Cooper Pair Pumping

Date: 
2010-07-12
Author(s): 

J. P. Pekola, V. Brosco, M. Möttönen, P. Solinas, and A. Shnirman

Reference: 

Phys. Rev. Lett. 105, 030401 (2010)

One of the challenges of adiabatic control theory is the proper inclusion of the effects of dissipation. Here we study the adiabatic dynamics of an open two-level quantum system deriving a generalized master equation to consistently account for the combined action of the driving and dissipation. We demonstrate that in the zero-temperature limit the ground state dynamics is not affected by environment. As an example, we apply our theory to Cooper pair pumping, which demonstrates the robustness of ground state adiabatic evolution.

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