Spin-resolved electron waiting times in a quantum-dot spin valve

Abstract

We study the electronic waiting time distributions (WTDs) in a non-interacting quantum dot spin valve by varying spin polarization and the noncollinear angle between the magnetizations of the leads using scattering matrix approach. Since the quantum dot spin valve involves two channels (spin up and down) in both the incoming and outgoing channels, we study three different kinds of WTDs, which are two-channel WTD, spin-resolved single-channel WTD and cross-channel WTD. We analyze the behaviors of WTDs in short times, correlated with the current behaviors for different spin polarizations and noncollinear angles. Cross-channel WTD reflects the correlation between two spin channels and can be used to characterize the spin transfer torque process. We study the influence of the earlier detection on the subsequent detection from the perspective of cross-channel WTD, and define the influence degree quantity as the cumulative absolute difference between cross-channel WTDs and first passage time distributions to quantitatively characterize the spin flip process. The influence degree shows a similar behavior with spin transfer torque and can be a new pathway to characterize spin correlation in spintronics system.

Waiting time distributions in a two-level fluctuator coupled to a superconducting charge detector

“…Electron waiting times have been investigated for a wide range of physical systems including quantum dots, [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] coherent conductors, 36,37 molecular junctions, 38,39 and superconducting systems. [40][41][42][43][44][45][46] Distributions of waiting times contain complementary information on charge transport properties which is not necessarily encoded in the full counting statistics (FCS) and vice versa.…”

Electron waiting times in hybrid junctions with topological superconductors

“…In quantum dot systems, the tunneling of individual electrons can now be experimentally observed using single-electron detectors, and measurements of an electron waiting time distribution have recently been reported 30 . In coherent conductors, a measurement of the waiting time distribution seems more challenging, and only recently a quantum theory of an electron waiting time clock has been developed for normal-state conductors 41 with an extension to a spin-sensitive detector being outlined in subsequent work 87 . Recent measurements of the time-of-flight of single-electron excitations through a mesoscopic conductor provide a promising way for directly investigating real-time dynamics of emitted pulses 88,89 .…”

Counting quantum jumps: A summary and comparison of fixed-time and fluctuating-time statistics in electron transport

“…Scattering theory, for example, has been used to calculate waiting times in superconducting junctions [108][109][110], periodically driven transport [36,111], and coherent conductors [35,37,112]. As with the FCS, waiting times in the transient regime are generally calculated via the non-equilibrium Green's functions method [74], which has been used to analyse the role of spin [74,113] and molecular vibrations [114] in electron transport. Alongside these two methods, substantial research has followed Brandes' original formalism and calculated waiting times from quantum master equations.…”