16.20.Sq Superconducting qubits coupled to resonators

Photon condensation in circuit QED by engineered dissipation

Date: 
2012-05-01
Author(s): 

D. Marcos, A. Tomadin, S. Diehl, P. Rabl

Reference: 

New J. Phys. 14 055005
doi:10.1088/1367-2630/14/5/055005

We study photon condensation phenomena in a driven and dissipative array of superconducting microwave resonators. Specifically, we show that by using an appropriately designed coupling of microwave photons to superconducting qubits, an effective dissipative mechanism can be engineered, which scatters photons towards low-momentum states while conserving their number.

Hybrid Quantum Circuit with a Superconducting Qubit Coupled to a Spin Ensemble

Date: 
2011-11-21 - 2012-03-20
Author(s): 

Y. Kubo, C. Grezes, A. Dewes, T. Umeda, J. Isoya, H. Sumiya, N. Morishita, H. Abe, S. Onoda, T. Ohshima, V. Jacques, A. Dréau, J.-F. Roch, I. Diniz, A. Auffeves, D. Vion, D. Esteve, and P. Bertet

Reference: 

Phys. Rev. Lett. 107, 220501

We report the experimental realization of a hybrid quantum circuit combining a superconducting qubit and an ensemble of electronic spins. The qubit, of the transmon type, is coherently coupled to the spin ensemble consisting of nitrogen-vacancy centers in a diamond crystal via a frequency-tunable superconducting resonator acting as a quantum bus. Using this circuit, we prepare a superposition of the qubit states that we store into collective excitations of the spin ensemble and retrieve back into the qubit later on.

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.

Geometric quantum gates with superconducting qubits

Date: 
2011-06-15
Author(s): 

I. Kamleitner, P. Solinas, C. Müller, A. Shnirman, and M. Möttönen

Reference: 

Phys. Rev. B 83, 214518 (2011)

We suggest a scheme to implement a universal set of non-Abelian geometric transformations for a single logical qubit composed of three superconducting qubits coupled to a single cavity. The scheme utilizes an adiabatic evolution in a rotating frame induced by the effective tripod Hamiltonian which is achieved by longitudinal driving of the qubits. The proposal is experimentally feasible with the current state of the art and could serve as a first proof of principle for geometric quantum computing.

Syndicate content