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144 results on '"Sørensen, Anders Søndberg"'

101. Environment-assisted precision measurement

Author

Goldstein, G., Cappellaro, P., Maze, J. R., Hodges, J. S., Jiang, L., Sørensen, Anders Søndberg, Lukin, M. D., Goldstein, G., Cappellaro, P., Maze, J. R., Hodges, J. S., Jiang, L., Sørensen, Anders Søndberg, and Lukin, M. D.

Abstract

We describe a method to enhance the sensitivity of precision measurements that takes advantage of the environment of a quantum sensor to amplify the response of the sensor to weak external perturbations. An individual qubit is used to sense the dynamics of surrounding ancillary qubits, which are in turn affected by the external field to be measured. The resulting sensitivity enhancement is determined by the number of ancillas that are coupled strongly to the sensor qubit; it does not depend on the exact values of the coupling strengths and is resilient to many forms of decoherence. The method achieves nearly Heisenberg-limited precision measurement, using a novel class of entangled states. We discuss specific applications to improve clock sensitivity using trapped ions and magnetic sensing based on electronic spins in diamond

Published
2011

102. Dissipative preparation of entanglement in optical cavities

Author

Kastoryano, Michael James, Reiter, Florentin, Sørensen, Anders Søndberg, Kastoryano, Michael James, Reiter, Florentin, and Sørensen, Anders Søndberg

Abstract

We propose a novel scheme for the preparation of a maximally entangled state of two atoms in an optical cavity. Starting from an arbitrary initial state, a singlet state is prepared as the unique fixed point of a dissipative quantum dynamical process. In our scheme, cavity decay is no longer undesirable, but plays an integral part in the dynamics. As a result, we get a qualitative improvement in the scaling of the fidelity with the cavity parameters. Our analysis indicates that dissipative state preparation is more than just a new conceptual approach, but can allow for significant improvement as compared to preparation protocols based on coherent unitary dynamics

Published
2011

103. Quantum entanglement between an optical photon and a solid-state spin qubit

Author

Togan, E., Chu, Y., Trifonov, A. S., Jiang, L., Maze, J., Childress, L., Dutt, M. V. G., Sørensen, Anders Søndberg, Hemmer, R., Zibrov, A. S., Lukin, M. D., Togan, E., Chu, Y., Trifonov, A. S., Jiang, L., Maze, J., Childress, L., Dutt, M. V. G., Sørensen, Anders Søndberg, Hemmer, R., Zibrov, A. S., and Lukin, M. D.

Abstract

Udgivelsesdato: 5 August

Published
2010

104. Scalable quantum networks based on few-qubit registers

Author

Jiang, Liang, Taylor, Jacob M., Sørensen, Anders Søndberg, Lukin, Mikhail D., Jiang, Liang, Taylor, Jacob M., Sørensen, Anders Søndberg, and Lukin, Mikhail D.

Abstract

Udgivelsesdato: 3 August

Published
2010

105. Adiabatic preparation of many-body states in optical lattices

Author

Sørensen, Anders Søndberg, Altman, Ehud, Gullans, Michael, D. Lukin, Mikhail, Demler, Eugene, Porto, J. V., Sørensen, Anders Søndberg, Altman, Ehud, Gullans, Michael, D. Lukin, Mikhail, Demler, Eugene, and Porto, J. V.

Abstract

Udgivelsesdato: 22 June

Published
2010

111. Hybrid long-distance entanglement distribution protocol

Author

Brask, Jonatan Bohr, Rigas, I., Polzik, Eugene Simon, Ansersen, U. L., Sørensen, Anders Søndberg, Brask, Jonatan Bohr, Rigas, I., Polzik, Eugene Simon, Ansersen, U. L., and Sørensen, Anders Søndberg

Abstract

We propose a hybrid (continuous-discrete variable) quantum repeater protocol for long-distance entanglement distribution. Starting from states created by single-photon detection, we show how entangled coherent state superpositions can be generated by means of homodyne detection. We show that near-deterministic entanglement swapping with such states is possible using only linear optics and homodyne detectors, and we evaluate the performance of our protocol combining these elements. Udgivelsesdato: 11 October

Published
2010

112. Quantum emitters coupled to surface plasmons of an nanowire:A Green's function approach

Author

Dzsotjan, David, Sørensen, Anders Søndberg, Fleischhauer, Michael, Dzsotjan, David, Sørensen, Anders Søndberg, and Fleischhauer, Michael

Abstract

We investigate a system consisting of a single, as well as two emitters strongly coupled to surface plasmon modes of a nanowire using a Green's function approach. Explicit expressions are derived for the spontaneous decay rate into the plasmon modes and for the atom-plasmon coupling as well as a plasmon-mediated atom-atom coupling. Phenomena due to the presence of losses in the metal are discussed. In case of two atoms, we observe Dicke subradiance and superradiance resulting from their plasmon-mediated interaction. Based on this phenomenon, we propose a scheme for a deterministic two-qubit quantum gate. We also discuss a possible realization of interesting many-body Hamiltonians, such as the spin-boson model, using strong emitter-plasmon coupling. Udgivelsesdato: 27 August

Published
2010

113. Antiferromagnetic noise correlations in optical lattices

Author

Bruun, Niels Bohr International Academy, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark, Georg Morten, Syljuåsen, F. T., Pedersen, K. G. L., Andersen, Brian Møller, Demler, E., Sørensen, Anders Søndberg, Bruun, Niels Bohr International Academy, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark, Georg Morten, Syljuåsen, F. T., Pedersen, K. G. L., Andersen, Brian Møller, Demler, E., and Sørensen, Anders Søndberg

Abstract

We analyze how noise correlations probed by time-of-flight experiments reveal antiferromagnetic (AF) correlations of fermionic atoms in two-dimensional and three-dimensional optical lattices. Combining analytical and quantum Monte Carlo calculations using experimentally realistic parameters, we show that AF correlations can be detected for temperatures above and below the critical temperature for AF ordering. It is demonstrated that spin-resolved noise correlations yield important information about the spin ordering. Finally, we show how to extract the spin correlation length and the related critical exponent of the AF transition from the noise Udgivelsesdato: September 18

Published
2009

115. Multimode model for projective photon-counting measurements

Author

Tualle-Brouri, Rosa, Ourjoumtsev, Alexei, Dantan, Aurelien, Grangier, Philippe, Wubs, Martijn, Sørensen, Anders Søndberg, Tualle-Brouri, Rosa, Ourjoumtsev, Alexei, Dantan, Aurelien, Grangier, Philippe, Wubs, Martijn, and Sørensen, Anders Søndberg

Abstract

Udgivelsesdato: 9 July

Published
2009

116. Demonstration of quadrature-squeezed surface plasmons in a gold waveguide

Author

Huck, Alexander, Smolka, Stephan, Lodahl, Peter, Sørensen, Anders Søndberg, Boltasseva, Alexandra, Janousek, Jiri, Andersen, Ulrik L., Huck, Alexander, Smolka, Stephan, Lodahl, Peter, Sørensen, Anders Søndberg, Boltasseva, Alexandra, Janousek, Jiri, and Andersen, Ulrik L.

Abstract

quantum optics Udgivelsesdato: 19 June

Published
2009

119. Three-dimensional theory for light-matter interaction

Author

Sørensen, Martin Westring, Sørensen, Anders Søndberg, Sørensen, Martin Westring, and Sørensen, Anders Søndberg

Abstract

Udgivelsesdato: 25 Januar, We present a full quantum mechanical three dimensional theory describing an electromagnetic field interacting with an ensemble of identical atoms. The theory is constructed such that it describes recent experiments on light-matter quantum interfaces, where the quantum fluctuations of light are mapped onto the atoms and back onto light. We show that the interaction of the light with the atoms may be separated into a mean effect of the ensemble and a deviation from the mean. The mean effect of the interaction effectively give rise to an index of refraction of the gas. We formally change to a dressed state picture, where the light modes are solutions to the diffraction problem, and develop a perturbative expansion in the fluctuations. The fluctuations are due to quantum fluctuations as well as the random positions of the atoms. In this perturbative expansion we show how the quantum fluctuations are mapped between atoms and light while the random positioning of the atoms give rise to decay due to spontaneous emission. Furthermore we identify limits, where the full three dimensional theory reduce to the one dimensional theory typically used to describe the interaction.

Published
2008

122. Spin squeezing of atomic ensembles via nuclear-electronic spin entanglement

Author

Fernholz, Thomas, Krauter, Hanna, Jensen, Kasper, Sherson, Jacob Friis, Sørensen, Anders Søndberg, Polzik, Eugene Simon, Fernholz, Thomas, Krauter, Hanna, Jensen, Kasper, Sherson, Jacob Friis, Sørensen, Anders Søndberg, and Polzik, Eugene Simon

Abstract

Udgivelsesdato: 15. August, We demonstrate spin squeezing in a room temperature ensemble of 1012 Cesium atoms using their internal structure, where the necessary entanglement is created between nuclear and electronic spins of each individual atom. This state provides improvement in measurement sensitivity beyond the standard quantum limit for quantum memory experiments and applications in quantum metrology and is thus a complementary alternative to spin squeezing obtained via inter-atom entanglement. Squeezing of the collective spin is verified by quantum state tomography.

Published
2008

123. Optimal control of light pulse storage and retrieval

Author

Novikova, Irina, Gorshkov, Alexey V., Phillips, David F., Sørensen, Anders Søndberg, Lukin, Mikhail D., Walsworth, Ronald L., Novikova, Irina, Gorshkov, Alexey V., Phillips, David F., Sørensen, Anders Søndberg, Lukin, Mikhail D., and Walsworth, Ronald L.

Abstract

Udgivelsesdato: June 15

Published
2007

124. Spin-photon entangling diode

Author

Flindt, Christian, Lukin, Mikhail D., Sørensen, Anders Søndberg, Taylor, Jacob M., Flindt, Christian, Lukin, Mikhail D., Sørensen, Anders Søndberg, and Taylor, Jacob M.

Abstract

Udgivelsesdato: 14 June

Published
2007

125. Universal approach to optimal photon storage in atomic media

Author

Gorshkov, Alexey V., André, Axel, Fleischhauer, Michael, Sørensen, Anders Søndberg, Lukin, Mikhail D., Gorshkov, Alexey V., André, Axel, Fleischhauer, Michael, Sørensen, Anders Søndberg, and Lukin, Mikhail D.

Abstract

Udgivelsesdato: March 23

Published
2007

127. Strong coupling of single emitters to surface plasmons

Author

Chang, Darrick E., Sørensen, Anders Søndberg, Hemmer, P. R., Lukin, M. D., Chang, Darrick E., Sørensen, Anders Søndberg, Hemmer, P. R., and Lukin, M. D.

Abstract

Udgivelsesdato: 18 July

Published
2007

133. A single-photon transistor using nanoscale surface plasmons

Author

Chang, Darrick E, Sørensen, Anders Søndberg, Demler, Eugene A., Lukin, Mikhail D., Chang, Darrick E, Sørensen, Anders Søndberg, Demler, Eugene A., and Lukin, Mikhail D.

Abstract

Udgivelsesdato: 26 August

Published
2007

135. Spin-orbit mediated control of spin qubits

Author

Flindt, C, Sørensen, Anders Søndberg, Flensberg, Karsten, Flindt, C, Sørensen, Anders Søndberg, and Flensberg, Karsten

Abstract

Spin-orbit interaction, quantum dots Udgivelsesdato: Dec. 15

Published
2006

136. Quantum optics with surface plasmons

Author

Chang, D.E, Sørensen, Anders Søndberg, Hemmer, P.R, Lukin, M.D, Chang, D.E, Sørensen, Anders Søndberg, Hemmer, P.R, and Lukin, M.D

Abstract

Multidisciplinary, physics Udgivelsesdato: August 4

Published
2006

137. Light qubit storage and retrieval using macroscopic atomic ensembles

Author

Sherson, J. F., Fiurásek, J., Mølmer, K., Sørensen, Anders Søndberg, Polzik, Eugene Simon, Sherson, J. F., Fiurásek, J., Mølmer, K., Sørensen, Anders Søndberg, and Polzik, Eugene Simon

Abstract

Quantum memory, Faraday interaction, photonic qubit Udgivelsesdato: 14 July

Published
2006

144. Strongly modified plasmon-matter interaction with mesoscopic quantum emitters.

Author

Andersen, Mads Lykke, Stobbe, Søren, Sørensen, Anders Søndberg, and Lodahl, Peter

Subjects
QUANTUM dots, NANOSTRUCTURES, SEMICONDUCTORS, PLASMONS (Physics), MESOSCOPIC phenomena (Physics), SOLID-state lasers, PHOTON emission, ATOMIC structure
Abstract

Semiconductor quantum dots (QDs) provide useful means to couple light and matter in applications such as light-harvesting and all-solid-state quantum information processing. This coupling can be increased by placing QDs in nanostructured optical environments such as photonic crystals or metallic nanostructures that enable strong confinement of light and thereby enhance the light-matter interaction. It has thus far been assumed that QDs can be described in the same way as atomic photon emitters-as point sources with wavefunctions whose spatial extent can be disregarded. Here we demonstrate that this description breaks down for QDs near plasmonic nanostructures. We observe an eightfold enhancement of the plasmon excitation rate, depending on QD orientation as a result of their mesoscopic character. Moreover, we show that the interaction can be enhanced or suppressed, determined by the geometry of the plasmonic nanostructure, consistent with a newly developed theory that takes mesoscopic effects into account. This behaviour has no equivalence in atomic systems and offers new opportunities to exploit the unique mesoscopic characteristics of QDs in the development of nanophotonic devices that use the increased light-matter interaction. [ABSTRACT FROM AUTHOR]

Published
2011
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