The vie wW cn oncluions cotIn i kl dosmnut we duo of do. authors endlAauld not be nepee as neoeuw... more The vie wW cn oncluions cotIn i kl dosmnut we duo of do. authors endlAauld not be nepee as neoeuwily representin dw offidde policies, sidue xpramd or knpOWe, of goe Defnm dveneed ResearchProjects Agncy or thetiod Status ownnt ITh docmenh r C) 1rn dW Mt Mf Odbr 00~u
Conference on Lasers and Electro-Optics/International Quantum Electronics Conference and Photonic Applications Systems Technologies, 2004
... effect [4] and laser cooling (which also enables the gate work at room temperature). Simulati... more ... effect [4] and laser cooling (which also enables the gate work at room temperature). Simulations based on the S-matrix theory show that a nonlinear phase-shift of a tenth of πcan be obtained with realistic parameters. This work was supported in part by NSF, ARDA/ARO, and ...
... first order in strain (Whitfield 1961). These deformation parameters iBAp(n, k) are important... more ... first order in strain (Whitfield 1961). These deformation parameters iBAp(n, k) are important in the electron-phonon interaction of semiconductors, and have been estimated from the transport properties (Bardeen and Shockley 1950, Herring and Vogt 1956, 1957, Aubrey, Gubler ...
The public reporting burden for this collection of information is estimated to average 1 hour per... more The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggesstions for reducing this burden, to Washington
Abstract Our studies of the determination of the transition temperature from the non-phonon mecha... more Abstract Our studies of the determination of the transition temperature from the non-phonon mechanisms is reviewed. Raising T c by replacing phonons with high frequency excitations does appear possible though the usual estimates are found to be too high.
Proceedings of the 17th International Conference on the Physics of Semiconductors, 1985
We report an investigation of the polarization of optical emission that probes the character of t... more We report an investigation of the polarization of optical emission that probes the character of the highest valence subband ho of GaAs-(AlGa)As quantum well heterostructures. The results reveal that for small in plane wavevectors k, a surprisingly large (~30%) admixture of the \( \left| {\frac{3}{2} \pm \frac{1}{2} > } \right. \) angular momentum representation is evident in ho. Further, at higher k ≈ 106cm−1 the character changes continously and tends to a completely mixed \( \left| {\frac{3}{2} \pm \frac{3}{2} > } \right.,\left| {\frac{3}{2}} \right. \pm \frac{1}{2} > \) state. Attempts to interpret these results within the effective mass approximation and coupling with Luttinger Hamiltonian yield large quantitative disagreement, especially near k=0. Several other mechanisms that could improve the theoretical understanding are found to be inadequate.
After reviewing the physical systems that may host exciton condensation, this chapter illustrates... more After reviewing the physical systems that may host exciton condensation, this chapter illustrates some recent proposals concerning the detection of coherent exciton flow. It focuses on the exciton analogues of two phenomena—Andreev reflection and the Josephson effect—which are hallmarks of superconducting behavior and stress the crucial differences between excitons and Cooper pairs. It shows that the excitonic insulator is the perfect insulator in terms of both charge and heat transport, with an unusually high resistance at the interface with a semimetal—the normal phase of the condensed state. Such behavior may be explained in terms of the coherence induced into the semimetal by the proximity of the exciton condensate. The exciton superflow may be directly probed in the case that excitons are optically pumped in a double-layer semiconductor heterostructure. The chapter proposes a correlated photon counting experiment for coupled electrostatic exciton traps.
Dynamics of entanglement of a two state system with a bath of a large but finite number of intera... more Dynamics of entanglement of a two state system with a bath of a large but finite number of interacting particles is used to show how the two state coherence is lost and can be recovered.
A survey of the current theoretical understanding of the spin relaxation processes of electrons a... more A survey of the current theoretical understanding of the spin relaxation processes of electrons and holes in confined systems of quasi-two dimensions is given. The theoretical framework is used to form a bridge between the electronic properties and the recent time-resolved polarization measurements. Spin relaxation mechanisms surveyed include single-particle spin flips via spin-orbit interaction and electron-hole-pair spin flips via exchange interaction.
The vie wW cn oncluions cotIn i kl dosmnut we duo of do. authors endlAauld not be nepee as neoeuw... more The vie wW cn oncluions cotIn i kl dosmnut we duo of do. authors endlAauld not be nepee as neoeuwily representin dw offidde policies, sidue xpramd or knpOWe, of goe Defnm dveneed ResearchProjects Agncy or thetiod Status ownnt ITh docmenh r C) 1rn dW Mt Mf Odbr 00~u
Conference on Lasers and Electro-Optics/International Quantum Electronics Conference and Photonic Applications Systems Technologies, 2004
... effect [4] and laser cooling (which also enables the gate work at room temperature). Simulati... more ... effect [4] and laser cooling (which also enables the gate work at room temperature). Simulations based on the S-matrix theory show that a nonlinear phase-shift of a tenth of πcan be obtained with realistic parameters. This work was supported in part by NSF, ARDA/ARO, and ...
... first order in strain (Whitfield 1961). These deformation parameters iBAp(n, k) are important... more ... first order in strain (Whitfield 1961). These deformation parameters iBAp(n, k) are important in the electron-phonon interaction of semiconductors, and have been estimated from the transport properties (Bardeen and Shockley 1950, Herring and Vogt 1956, 1957, Aubrey, Gubler ...
The public reporting burden for this collection of information is estimated to average 1 hour per... more The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggesstions for reducing this burden, to Washington
Abstract Our studies of the determination of the transition temperature from the non-phonon mecha... more Abstract Our studies of the determination of the transition temperature from the non-phonon mechanisms is reviewed. Raising T c by replacing phonons with high frequency excitations does appear possible though the usual estimates are found to be too high.
Proceedings of the 17th International Conference on the Physics of Semiconductors, 1985
We report an investigation of the polarization of optical emission that probes the character of t... more We report an investigation of the polarization of optical emission that probes the character of the highest valence subband ho of GaAs-(AlGa)As quantum well heterostructures. The results reveal that for small in plane wavevectors k, a surprisingly large (~30%) admixture of the \( \left| {\frac{3}{2} \pm \frac{1}{2} > } \right. \) angular momentum representation is evident in ho. Further, at higher k ≈ 106cm−1 the character changes continously and tends to a completely mixed \( \left| {\frac{3}{2} \pm \frac{3}{2} > } \right.,\left| {\frac{3}{2}} \right. \pm \frac{1}{2} > \) state. Attempts to interpret these results within the effective mass approximation and coupling with Luttinger Hamiltonian yield large quantitative disagreement, especially near k=0. Several other mechanisms that could improve the theoretical understanding are found to be inadequate.
After reviewing the physical systems that may host exciton condensation, this chapter illustrates... more After reviewing the physical systems that may host exciton condensation, this chapter illustrates some recent proposals concerning the detection of coherent exciton flow. It focuses on the exciton analogues of two phenomena—Andreev reflection and the Josephson effect—which are hallmarks of superconducting behavior and stress the crucial differences between excitons and Cooper pairs. It shows that the excitonic insulator is the perfect insulator in terms of both charge and heat transport, with an unusually high resistance at the interface with a semimetal—the normal phase of the condensed state. Such behavior may be explained in terms of the coherence induced into the semimetal by the proximity of the exciton condensate. The exciton superflow may be directly probed in the case that excitons are optically pumped in a double-layer semiconductor heterostructure. The chapter proposes a correlated photon counting experiment for coupled electrostatic exciton traps.
Dynamics of entanglement of a two state system with a bath of a large but finite number of intera... more Dynamics of entanglement of a two state system with a bath of a large but finite number of interacting particles is used to show how the two state coherence is lost and can be recovered.
A survey of the current theoretical understanding of the spin relaxation processes of electrons a... more A survey of the current theoretical understanding of the spin relaxation processes of electrons and holes in confined systems of quasi-two dimensions is given. The theoretical framework is used to form a bridge between the electronic properties and the recent time-resolved polarization measurements. Spin relaxation mechanisms surveyed include single-particle spin flips via spin-orbit interaction and electron-hole-pair spin flips via exchange interaction.
Uploads
Papers by L. Sham