Sökning: "macroscopic quantum coherence"

Visar resultat 1 - 5 av 7 avhandlingar innehållade orden macroscopic quantum coherence.

  1. 1. Quantum Coherence and Quantum-Vacuum Effects in Some Artificial Electromagnetic Media

    Författare :Jianqi Shen; Sailing He; Chris Phillips; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Quantum coherence; quantum vacuum; electromagnetically induced transparency; negative refractive index; artificial electromagnetic media; electric- and magnetic-dipole transitions; multilevel atomic vapors; transient evolution; Electrical engineering; electronics and photonics; Elektroteknik; elektronik och fotonik;

    Sammanfattning : The author of this thesis concentrates his attention on quantum optical properties of some artificial electromagnetic media, such as quantum coherent atomic vapors (various multilevel electromagnetically induced transparency vapors) and negative refractive index materials, and suggests some possible ways to manipulate wave propagations inside the artificial electromagnetic materials based on quantum coherence and quantum vacuum effects. In Chapters 1 and 2, the author reviews the previous papers on quantum coherence as well as the relevant work such as electromagnetically induced transparency (EIT), atomic population trapping and their various applications. LÄS MER

  3. 2. Quantum Resources for Efficient Excitation Energy Transfer in Natural and Artificial Pigment-Protein Molecular Aggregates

    Författare :Charlotta Bengtson; Erik Sjöqvist; Susana Huelga; Uppsala universitet; []
    Nyckelord :Quantum coherence; quantum correlations; quantum nonlocality; open quantum systems; non-Markovian dynamics; Kemi med inriktning mot kvantkemi; Chemistry with specialization in Quantum Chemistry;

    Sammanfattning : Recently, long-lasting quantum effects in a number of photosynthetic complexes, which are pigment-protein molecular aggregates (PPMAs), were experimentally verified. These findings created an interest in trying to connect the known highly efficient excitation energy transfer (EET) in these systems to the existence of quantum effects such as quantum coherence and quantum correlations. LÄS MER

  4. 3. The Single Cooper Pair Box - a Quantum-Mechanical Electronic Circuit

    Författare :David Gunnarsson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; quantum capacitance; quantum computing; single Cooper-pair box; SET; radio-frequency single-electron-transistor; macroscopic quantum coherence; Qubit;

    Sammanfattning : In this thesis the single Cooper pair box (SCB) is investigated with a radio frequency single electron transistor (RF-SET). The RF-SET is used as an electrometer to detect the charge of the SCB. The SCB can be regarded as a quantum two-level system and could therefore be a possible qubit. LÄS MER

  5. 4. Read-out of superconducting qubits - a quantum measurement process

    Författare :Lars Tornberg; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; superconducting qubits; single Cooper Pair box; quantum measurements; quantum electrical circuits; quatum computing;

    Sammanfattning : In this work we consider measurements on quantum systems emphasizingon read-out of superconducting qubits. The qubit is always coupled to anenvironment, containing a macroscopic number of degrees of freedom. Thisperturbs the qubit and destroys the phase coherence of the quantum state. LÄS MER

  7. 5. Quantum dynamics of spin active and d-wave Josephson junctions

    Författare :Jens Harro Michelsen; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Josephson effect; macroscopic quantum tunneling; high-temperature superconducvity; superconducting junctions; spin-active junctions; nonequilibrium superconductivity; Andreev bound states;

    Sammanfattning : Conventional tunnel Josephson junctions form the basic building blocks of superconducting electronics. Their operation is based on comparatively simple dynamics where the superconducting phases across the junctions is the only dynamical degree of freedom. LÄS MER