01.10.+i Encoding, processing and transmission of information via physical systems

Quantum Information Processing with Atom Chips

Date: 
2011-02-14
Author(s): 

P. Treutlein, A. Negretti, and T. Calarco

Reference: 

in: "Atom Chips", ed. by J. Reichel and V. Vuletic (Wiley-VCH, Weinheim, Germany, 2011), pp. 283-308
doi: 10.1002/9783527633357.ch9

Quantum-Dot-Spin Single-Photon Interface

Date: 
2010-07-15
Author(s): 

S. T. Yılmaz, P. Fallahi, and A. Imamoğlu

Reference: 

Phys. Rev. Lett. 105, 033601 (2010)

Using background-free detection of spin-state-dependent resonance fluorescence from a single-electron charged quantum dot with an efficiency of 0.1%, we realize a classical single spin-photon interface where the detection of a scattered photon with 300 ps time resolution projects the quantum dot spin to a definite spin eigenstate with fidelity exceeding 99%. The bunching of resonantly scattered photons reveals information about electron spin dynamics.

Defect center room-temperature quantum processors

Date: 
2010-05-25
Author(s): 

J. Wrachtrup

Reference: 

Proceedings of the National Academy of Sciences of the United States of America 107, 9479-9480 (21)

Quantum information devices promise unique opportunities in information technology. Physicists are intrigued with building such devices because they probe our understanding of the nature of quantum mechanics. Quantum effects, although providing the basis of atomic, molecular, and solid state physics, usually are not observed in everyday life because the highly fragile nature of coherence and entanglement requires extensive shielding against environmental effects.

Quantum register based on coupled electron spins in a room-temperature solid

Date: 
2010-02-28
Author(s): 

P. Neumann, R. Kolesov, B. Naydenov, J. Beck1, F. Rempp, M. Steiner, V. Jacques, G. Balasubramanian, M. L. Markham, D. J. Twitchen, S. Pezzagna, J. Meijer, J. Twamley, F. Jelezko & J. Wrachtrup

Reference: 

Nature Physics 6, 249-253 (2010)

Devices that harness the laws of quantum physics hold the promise for information processing that outperforms their classical counterparts, and for unconditionally secure communication. However, in particular, implementations based on condensed-matter systems face the challenge of short coherence times. Carbon materials, particularly diamond, however, are suitable for hosting robust solid-state quantum registers, owing to their spin-free lattice and weak spin–orbit coupling.

Single-Shot Readout of a Single Nuclear Spin

Date: 
2010-07-01
Author(s): 

Philipp Neumann, Johannes Beck, Matthias Steiner, Florian Rempp, Helmut Fedder, Philip R. Hemmer, Jörg Wrachtrup and Fedor Jelezko

Reference: 

Science 329 no. 5991 pp. 542-544

Projective measurement of single electron and nuclear spins has evolved from a gedanken experiment to a problem relevant for applications in atomic-scale technologies like quantum computing. Although several approaches allow for detection of a spin of single atoms and molecules, multiple repetitions of the experiment that are usually required for achieving a detectable signal obscure the intrinsic quantum nature of the spin’s behavior.

Quantum gate in the decoherence-free subspace of trapped-ion qubits

Date: 
2010-11-23
Reference: 

P. Ivanov, U.G. Poschinger, K. Singer, F. Schmidt-Kaler
Europhysics Letters 92, 30006 (2010)
http://arxiv.org/abs/0909.5397

We propose a geometric phase gate in a decoherence-free subspace with trapped ions. The quantum information is encoded in the Zeeman sublevels of the ground-state and two physical qubits to make up one logical qubit with ultra long coherence time. Single- and two-qubit operations together with the transport and splitting of linear ion crystals allow for a robust and decoherence-free scalable quantum processor. For the ease of the phase gate realization we employ one Raman laser field on four ions simultaneously, i.e. no tight focus for addressing.

Trapped ions as quantum bits: Essential numerical tools (Colloquium)

Date: 
2010-09-14
Author(s): 

K. Singer, U. Poschinger, M. Murphy, P. Ivanov, F. Ziesel, T. Calarco, F. Schmidt-Kaler

Reference: 

Rev. Mod. Phys. 82, 2609 (2010)

Trapped laser-cooled atoms and ions are quantum systems which can be experimentally controlled with an as yet unmatched degree of precision. Due to the control of the motion and the internal degrees of freedom, these quantum systems can be adequately described by a well-known Hamiltonian. In this colloquium, powerful numerical tools for the optimization of the external control of the motional and internal states of trapped neutral atoms, explicitly applied to the case of trapped laser-cooled ions in a segmented ion-trap are presented.

Syndicate content