Coherence and Quantum Noise in Mesoscopic Physics
Yoseph Imry, WIS, 01/08
• Most of Mesoscopics has to do with interference-- coherence necessary.
• Decoherence due to “inelastic” scattering -- interaction with the dynamic noise of the environment.
OUTLINE OF TALK QUANTUM NOISE (Gavish, Levinson) DEPHASING (Stern, Aharonov) • Quantum noise, Physics of Power • Inelasticity - change of state of Spectrum environment. • Fluctuation-Dissipation Theorem, in • Disordered conductors -- especially steady state low dimensions. • Shot-Noise, Excess noise, • Nonequilibrium dephasing by dependence on full state of system “quantum detector”. • What is detected in a quantum noise • Low-temperature limit ??? and in an excess noise measurement? • Recovery of Interference. • Heisenberg Constraints on Quantum Amps’ (Yurke) A-B Flux in an isolated ring
• A-B flux equivalent to boundary condition. • Physics periodic in flux, period h/e (Byers-Yang ). • “Persistent currents”exist due to flux. • They do not decay by impurity scattering ( BIL ).
Two-slit interference--a quintessential QM example:
““Two slit formula ”” When is it valid??? Closed system! scatterer
scatterer h/e osc. –mesoscopic fluctuation. Compare: h/2e osc. – impurity-ensemble average,
Altshuler, Aronov, Spivak, Sharvin 2 Aharonov Bohm Oscillation in mesoscopic interferometer (Heiblum)