Modeling shallow confinement in tuneable quantum dots

Abstract

This paper proposes a universal microscopic model for the shallow confinement regime of single-electron tunneling devices. We consider particle escape from a quantum well generically emerging as a bifurcation in a smooth electrostatic potential and develop a set of analytic and numerical approximations for the ground-state tunneling and thermally activated escape rates. These approximations are applied to the problem of electron capture by a closing tunnel barrier where the competition between the closing speed and the escape rate defines a scaling relation for the capture fidelity. Effective one-dimensional cubic potential approximation leads to a universal form of this scaling relation in terms of device-independent dimensionless depth and speed parameters. Using predictions for temperature and magnetic-field dependence we show how to infer the energy scales of cubic longitudinal and quadratic transverse confinement. Finally, we derive an intrinsic quantum speed bound for adiabatic protection of the ground state tunneling and show that the latter can potentially be exploited up to the break down of confinement with a practical speed limit set by reaching the quantum uncertainty of the barrier height before the onset of non-adiabatic excitation. These results contribute to mapping out the physical limits of single-electron quantum technologies for electrical metrology and sensing.

Final version accepted by Physical Review B

References in corpus (16)

• Circuit Quantum Electrodynamics
• An On-Demand Coherent Single Electron Source
• Single-parameter non-adiabatic quantized charge pumping
• Coherent Particle Transfer in an On-Demand Single-Electron Source
• Partitioning of on-demand electron pairs
• Single-parameter quantized charge pumping in high magnetic fields
• Generation of energy selective excitations in quantum Hall edge states
• Enhanced current quantization in high frequency electron pumps in a perpendicular magnetic field
• Evidence for universality of tunable-barrier electron pumps
• Quantum fluctuations and coherence in high-precision single-electron capture
• Ultrafast Emission and Detection of a Single-Electron Gaussian Wave Packet: A Theoretical Study
• Coulomb-mediated antibunching of an electron pair surfing on sound
• Two electrons interacting at a mesoscopic beam splitter
• Coherent rotations of a single spin-based qubit in a single quantum dot at fixed Zeeman energy
• A random-walk benchmark for single-electron circuits
• Spectroscopy of hot-electron pair emission from a driven quantum dot

Cited by in corpus (1)

• Universal scaling of adiabatic tunneling out of a shallow confinement potential