SOLID

Understanding entanglement sudden death through multipartite entanglement and quantum correlations

Date: 
2010-03-10
Author(s): 

Jared H Cole

Reference: 

J. Phys. A: Math. Theor. 43, 135301 (2010)

The effect of entanglement sudden death (ESD) can arise when entangling interactions convert purely bipartite entangled states into more generally entangled states. As a result, ESD can also be seen as a function of partitioning of the system, not just of time, as the system partitioning defines different (multipartite) entanglement classes.

Single-qubit lasing in the strong-coupling regime

Date: 
2010-11-03
Author(s): 

Stephan André, Pei-Qing Jin, Valentina Brosco, Jared H. Cole, Alessandro Romito, Alexander Shnirman, and Gerd Schön

Reference: 

Phys. Rev. A 82, 053802 (2010)

Superconducting micromasers

Date: 
2009-06-23
Author(s): 

S. André, V. Brosco, A. Shnirman, and G. Schön

Reference: 

Physica E 42, 444-448 (2010)

Recent experiments demonstrated the possibility to realize a single-qubit maser, by coupling an electrical resonator to a superconducting qubit. In the present paper we extend earlier work on single-atom lasers to account for the strong qubit–resonator coupling. We focus in particular on the spectral properties of the lasing radiation and we discuss phase locking induced by an additional ac driving of the resonator.

Tuning the Exciton Binding Energies in Single Self-Assembled InGaAs/GaAs Quantum Dots by Piezoelectric-Induced Biaxial Stress

Date: 
2010-02-12
Author(s): 

F. Ding, R. Singh, J. D. Plumhof, T. Zander, V. Křápek1, Y. H. Chen2, M. Benyoucef1, V. Zwiller, K. Dörr, G. Bester, A. Rastelli, and O. G. Schmidt

Reference: 

Phys. Rev. Lett. 104, 067405 (2010)

Linewidth narrowing and Purcell enhancement in photonic crystal cavities on an Er-doped silicon nitride platform

Date: 
2010-01-25
Author(s): 

Yiyang Gong, Maria Makarova, Selçuk Yerci, Rui Li, Martin J. Stevens, Burm Baek, Sae Woo Nam, Robert H. Hadfield, Sander N. Dorenbos, Val Zwiller, Jelena Vuckovic, and Luca Dal Negro

Reference: 

Optics Express, Vol. 18, Issue 3, pp. 2601-2612 (2010)

Light emission at 1.54 μm from an Er-doped amorphous silicon nitride layer coupled to photonic crystal resonators at cryogenic and room temperatures and under varying optical pump powers has been studied. The results demonstrate that small mode volume, high quality factor resonators enhance Er absorption and emission rates at the cavity resonance. Time resolved measurements give 11- to 17-fold Purcell enhancement of spontaneous emission at cryogenic temperatures, and 2.4-fold enhancement at room temperature.

Single Electron Charging in Optically Active Nanowire Quantum Dots

Date: 
2010-04-13
Author(s): 

Maarten P. van Kouwen, Michael E. Reimer, Anne W. Hidma, Maarten H. M. van Weert, Rienk E. Algra, Erik P. A. M. Bakkers, Leo P. Kouwenhoven and Val Zwiller

Reference: 

Nano Lett., 2010, 10 (5), pp 1817–1822

We report optical experiments of a charge tunable, single nanowire quantum dot subject to an electric field tuned by two independent voltages. First, we control tunneling events through an applied electric field along the nanowire growth direction. Second, we modify the chemical potential in the nanowire with a back-gate.

Crystal Phase Quantum Dots

Date: 
2010-03-05
Author(s): 

N. Akopian, G. Patriarche, L. Liu, J.-C. Harmand and V. Zwiller

Reference: 

Nano Lett., 2010, 10 (4), pp 1198–1201

In semiconducting nanowires, both zinc blende and wurtzite crystal structures can coexist. The band structure difference between the two structures can lead to charge confinement. Here we fabricate and study single quantum dot devices defined solely by crystal phase in a chemically homogeneous nanowire and observe single photon generation.

Enhanced telecom wavelength single-photon detection with NbTiN superconducting nanowires on oxidized silicon

Date: 
2010-06-03
Author(s): 

M. G. Tanner, C. M. Natarajan, V. K. Pottapenjara, J. A. O’Connor, R. J. Warburton, R. H. Hadfield, B. Baek, S. Nam, S. N. Dorenbos, E. Bermúdez Ureña, T. Zijlstra, T. M. Klapwijk, and V. Zwiller

Reference: 

Appl. Phys. Lett. 96, 221109 (2010)

Superconducting nanowire single-photon detectors (SNSPDs) have emerged as a highly promising infrared single-photon detector technology. Next-generation devices are being developed with enhanced detection efficiency (DE) at key technological wavelengths via the use of optical cavities. Furthermore, new materials and substrates are being explored for improved fabrication versatility, higher DE, and lower dark counts. We report on the practical performance of packaged NbTiN SNSPDs fabricated on oxidized silicon substrates in the wavelength range from 830 to 1700 nm.

Surround-gated vertical nanowire quantum dots

Date: 
2010-06-11
Author(s): 

M. H. M. van Weert, M. den Heijer, M. P. van Kouwen, R. E. Algra, E. P. A. M. Bakkers, L. P. Kouwenhoven1, and V. Zwiller

Reference: 

Appl. Phys. Lett. 96, 233112 (2010)

We report voltage dependent photoluminescence experiments on single indium arsenide phosphide (InAsP) quantum dots embedded in vertical surround-gated indium phosphide (InP) nanowires. We show that by tuning the gate voltage, we can access different quantum dot charge states. We study the anisotropic exchange splitting by polarization analysis, and identify the neutral and singly charged exciton. These results are important for spin addressability in a charge tunable nanowire quantum dot.

 

Quantum optics: A spooky light-emitting diode

Date: 
2010-08-01
Author(s): 

Val Zwiller

Reference: 

Nature Photonics 4, 508 - 509 (2010)

The generation of entangled photon pairs is usually a complex process involving optically driven schemes and nonlinear optics. The recent demonstration of an electrically powered light-emitting diode that is capable of this task looks set to greatly simplify experiments in the field of quantum information processing.

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