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Dressed-State Amplification by a Single Superconducting Qubit

Mon, 2013-02-11 19:31 - Daniel Rudolph
Date: 
2013-01-30
Author(s): 

G. Oelsner, P. Macha, O. V. Astafiev, E. Il’ichev, M. Grajcar, U. Hübner, B. I. Ivanov, P. Neilinger, and H.-G. Meyer

Reference: 

Phys. Rev. Lett. 110, 053602 (2013)

URL: 

http://link.aps.org/doi/10.1103/PhysRevLett.110.053602

Heat cost of parametric generation of microwave squeezed states

Mon, 2013-02-11 19:28 - Daniel Rudolph
Date: 
2012-06-11
Author(s): 

A. M. Zagoskin, E. Il'ichev, and Franco Nori

Reference: 

Phys. Rev. A 85, 063811 (2012)

URL: 

http://link.aps.org/doi/10.1103/PhysRevA.85.063811

In parametric systems, squeezed states of radiation can be generated via extra work done by external sources. This eventually increases the entropy of the system despite the fact that squeezing is reversible. We investigate the entropy increase due to squeezing and show that it is quadratic in the squeezing rate and may become important in the repeated operation of tunable oscillators (quantum buses) used to connect qubits in various proposed schemes for quantum computing.

 

Relativistic Quantum Teleportation with superconducting circuits

Mon, 2013-02-11 19:24 - Daniel Rudolph
Date: 
2012-11-23
Author(s): 

N. Friis, A. R. Lee, K. Truong, C. Sabín, E. Solano, G. Johansson, and I. Fuentes

Reference: 

arXiv:1211.5563 [quant-ph]

URL: 

http://arxiv.org/abs/1211.5563

We study the effects of relativistic motion on quantum teleportation and propose a realizable experiment where our results can be tested. We compute bounds on the optimal fidelity of teleportation when one of the observers undergoes non-uniform motion for a finite time. The upper bound to the optimal fidelity is degraded due to the observer's motion however, we discuss how this degradation can be corrected. These effects are observable for experimental parameters that are within reach of cutting-edge superconducting technology.

Quantum Simulations of Relativistic Quantum Physics in Circuit QED

Mon, 2013-02-11 19:23 - Daniel Rudolph
Date: 
2012-11-16
Author(s): 

J. S. Pedernales, R. Di Candia, D. Ballester, E. Solano

Reference: 

arXiv:1211.3953 [quant-ph]

URL: 

http://arxiv.org/abs/1211.3953

We present a scheme for simulating relativistic quantum physics in circuit quantum electrodynamics. By using three classical microwave drives, we show that a superconducting qubit strongly-coupled to a resonator field mode can be used to simulate the dynamics of the Dirac equation and Klein paradox in all regimes. Using the same setup we also propose the implementation of the Foldy-Wouthuysen canonical transformation, after which the time derivative of the position operator becomes a constant of the motion.

Deterministic Generation of Arbitrary Symmetric States and Entanglement Classes

Mon, 2013-02-11 19:22 - Daniel Rudolph
Date: 
2012-11-02
Author(s): 

L. Lamata, C. E. Lopez, B. Lanyon, T. Bastin, J. C. Retamal, E. Solano

Reference: 

arXiv:1211.0404 [quant-ph]

URL: 

http://arxiv.org/abs/1211.0404

We propose a method to generate arbitrary symmetric states of N qubits, which can be easily associated with their entanglement classes. It is particularly suited to quantum optics systems like trapped ions or superconducting circuits. We encode each qubit in two metastable levels of the system and use a bosonic quantum bus for creating the states. The method is deterministic and relies on a sequence of selective unitary gates upon the qubits within the system coherence time.

Dynamical correlation functions and the quantum Rabi model

Mon, 2013-02-11 19:19 - Daniel Rudolph
Date: 
2013-02-08
Author(s): 

F. A. Wolf, F. Vallone, G. Romero, M. Kollar, E. Solano, and D. Braak

Reference: 

arXiv:1211.6469 [quant-ph], accepted in Physical Review A (2013)

URL: 

http://arxiv.org/abs/1211.6469

We study the quantum Rabi model within the framework of the analytical solution developed in Phys. Rev. Lett. 107,100401 (2011). In particular, through time-dependent correlation functions, we give a quantitative criterion for classifying two regions of the quantum Rabi model, involving the Jaynes-Cummings, the ultrastrong, and deep strong coupling regimes. In addition, we find a stationary qubit-field entangled basis that governs the whole dynamics as the coupling strength overcomes the mode frequency.

Path Entanglement of Continuous-Variable Quantum Microwaves

Mon, 2013-02-11 19:17 - Daniel Rudolph
Date: 
2012-12-18
Author(s): 

E. P. Menzel, R. Di Candia, F. Deppe, P. Eder, L. Zhong, M. Ihmig, M. Haeberlein, A. Baust, E. Hoffmann, D. Ballester, K. Inomata, T. Yamamoto, Y. Nakamura, E. Solano, A. Marx, R. Gross

Reference: 

Phys. Rev. Lett. 109, 250502 (2012)

URL: 

http://link.aps.org/doi/10.1103/PhysRevLett.109.250502

Encoding relativistic potential dynamics into free evolution

Mon, 2013-02-11 19:16 - Daniel Rudolph
Date: 
2012-05-02
Author(s): 

C. Sabín, J. Casanova, J. J. Garcia-Ripoll, L. Lamata, E. Solano, and J. León

Reference: 

Phys. Rev. A 85, 052301 (2012)

URL: 

http://link.aps.org/doi/10.1103/PhysRevA.85.052301

We propose a method to simulate a Dirac or Majorana equation evolving under particular potentials with the use of the corresponding free evolution, while the potential dynamics is encoded in a static transformation upon the initial state. We extend our results to interacting two-body systems.

 

Circuit quantum electrodynamics with a superconducting quantum point contact

Mon, 2013-02-11 19:14 - Daniel Rudolph
Date: 
2012-05-24
Author(s): 

G. Romero, I. Lizuain, V. S. Shumeiko, E. Solano, and F. S. Bergeret

Reference: 

Phys. Rev. B 85, 180506(R) (2012)

URL: 

http://link.aps.org/doi/10.1103/PhysRevB.85.180506

We consider a superconducting quantum point contact in a circuit quantum electrodynamics setup. We study three different configurations, attainable with current technology, where a quantum point contact is coupled galvanically to a coplanar waveguide resonator. Furthermore, we demonstrate that the strong and ultrastrong coupling regimes can be achieved with realistic parameters, allowing the coherent exchange between a superconducting quantum point contact and a quantized intracavity field.

 

Ultrafast Quantum Gates in Circuit QED

Mon, 2013-02-11 19:13 - Daniel Rudolph
Date: 
2012-03-19
Author(s): 

G. Romero, D. Ballester, Y. M. Wang, V. Scarani, and E. Solano

Reference: 

Phys. Rev. Lett. 108, 120501 (2012)

URL: 

http://link.aps.org/doi/10.1103/PhysRevLett.108.120501

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