Archive for May, 2008

Quantum phase transitions in photonic cavities with two-level systems

May 22nd, 2008  |  by  |  published in All, Papers, Research, Solid Light

Phys. Rev. A, 77, 5, 053819 (2008)

Systems of coupled photonic cavities have been predicted to exhibit quantum phase transitions by analogy with the Hubbard model. To this end, we have studied topologies of few (up to six) photonic cavities each containing a single two-level system. Quantum phase space diagrams are produced for these systems, and compared to mean-field results. We also consider finite effective temperature, and compare this to the notion of disorder. We find the extent of the Mott lobes shrink analogously to the conventional Bose-Hubbard model.

Colloquium @ Stanford: Spookytechnology and Society: The progress and implications of quantum information science and technology

May 21st, 2008  |  by  |  published in All, Talks

Speaker: Charles Tahan. About the talk: As a physicist, I will give a somewhat un-physics perspective on quantum information science and technology, both via some of my own scientific work, but mostly from the vantage of science and technology studies. My own pet name for the field, spookytechnology, provides a good starting point for the discussion. We will touch on why the new quantum revolution is for real (including some cool examples), what “new quantum revolution” actually means, why it’s more interesting than nanotechnology, and how we should prepare for it, both personally and societally.

Quantum Fluctuations, Temperature and Detuning Effects in Solid-Light Systems

May 20th, 2008  |  by  |  published in All, Papers

Phys. Rev. Lett. 100, 216401 (2008)

The superfluid to Mott insulator transition in cavity polariton arrays is analyzed using the variational cluster approach, taking into account quantum fluctuations exactly on finite length scales. Phase diagrams in one and two dimensions exhibit important non-mean-field features. Single-particle excitation spectra in the Mott phase are dominated by particle and hole bands separated by a Mott gap. In contrast to Bose-Hubbard models, detuning allows for changing the nature of the bosonic particles from quasi-localized excitons to polaritons to weakly interacting photons. The Mott state with density one exists up to temperatures $T/g\gtrsim0.03$, implying experimentally accessible temperatures for realistic cavity couplings $g$.

Tahan Research

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