Coherent-incoherent transition in a Cooper-pair-box coupled to a quantum oscillator: an equilibrium approach
نویسندگان
چکیده
Abstract: Temperature effect on quantum tunneling in a Cooper-pair-box coupled to a quantum oscillator is studied by both numerical and analytical calculations. It is found that, in strong coupling regions, coherent tunneling of a Cooper-pair-box can be destroyed by its coupling to a quantum oscillator and the tunneling becomes thermally activated as the temperature rises, leading to failure of the Cooper-pair-box. The transition temperature between the coherent tunneling and thermo-activated hopping is determined and physics analysis based on small polaron theory is also provided.
منابع مشابه
A ug 2 00 5 Quantum nano - electromechanics with electrons , quasiparticles and Cooper pairs : effective bath descriptions and strong feedback effects
Using a quantum noise approach, we discuss the physics of both normal metal and superconducting single electron transistors (SET) coupled to mechanical resonators. Particular attention is paid to the regime where transport occurs via incoherent Cooper-pair tunneling (either via the Josephson quasiparticle (JQP) or double Josephson quasiparticle (DJQP) process). We show that, surprisingly, the b...
متن کاملQuantum nano - electromechanics with electrons , quasiparticles and Cooper pairs : effective bath descriptions and strong feedback effects
Using a quantum noise approach, we discuss the physics of both normal metal and superconducting single electron transistors (SET) coupled to mechanical resonators. Particular attention is paid to the regime where transport occurs via incoherent Cooper-pair tunneling (either via the Josephson quasiparticle (JQP) or double Josephson quasiparticle (DJQP) process). We show that, surprisingly, the b...
متن کاملCharge Oscillations in Superconducting Nanodevices Coupled to External Environments
Charge oscillations in certain nanodevices, more specifically the so-called Superconducting Cooper Pair Boxes (SCB), are usually interpreted as an effect of macroscopic quantum coherence; an alternative explanation is however possible in terms of the Gross-Pitaewski equation for the classical order parameter. These two explanations are based on different quantum states assigned to the SCB, occu...
متن کاملThe Effect of Structural Parameters on the Electronic States and Oscillator Strength of a Resonant Tunneling Quantum Well Infrared Photodetector
In this paper a resonant tunnelling quantum well infrared photodetector (RT-QWIP) is discussed. Each period of this photodetector structure comprises of a resonant tunnelling structure (AlAs/AlGaAs/AlAs) nearby a quantum well (AlGaAs/GaAs). In this photodetector, photocurrent is produced when an electron makes a transition from the ground state of the well to an excited state which is coupled t...
متن کاملVariational approach to the Caldeira-Leggettmodel
We apply the displaced-oscillator variational ansatz to the Caldeira-Leggett model for a quantum particle in a one-dimensional box described by a tight-binding chain. We focus on the case of an Ohmic environment and study the phase diagram for different chain lengths. At zero temperature there is a phase transition to a localized phase when the number of sites is even. At finite temperature, a ...
متن کامل