Spin filtering through excited states in double quantum dot pumps

Abstract

Recently it has been shown that ac-driven double quantum dots can act as spin pumps and spin filters. By calculating the current through the system for each spin polarization, by means of the time evolution of the reduced density matrix in the sequential tunneling regime (Born-Markov approximation), we demonstrate that the spin polarization of the current can be controlled by tuning the parameters (amplitude and frequency) of the ac field. Importantly, the pumped current as a function of the applied frequency presents a series of peaks which are uniquely associated with a definite spin polarization. We discuss how excited states participating in the current allow the system to behave as a bipolar spin filter by tuning the ac frequency and intensity. We also discuss spin relaxation and decoherence effects in the pumped current and show that measuring the width of the current vs frequency peaks allows to determine the spin decoherence time $T_2$.

10 pages. 5 figures

References in corpus (5)

• Single-shot read-out of an individual electron spin in a quantum dot
• Single-shot readout of electron spin states in a quantum dot using spin-dependent tunnel rates
• Semiconductor few-electron quantum dot operated as a bipolar spin filter
• Adiabatic spin pumping through a quantum dot with a single orbital level
• Photovoltaic and Rectification Currents in Quantum Dots

Cited by in corpus (4)

• Resonance fluorescence in driven quantum dots: electron and photon correlations
• Coherent spin rotations in open driven double quantum dots
• Spin correlations in spin blockade
• Shot noise in a quantum dot coupled to non-magnetic leads: Effects of Coulomb interaction