Electric Dipole Spin Resonance for Heavy Holes in Quantum Dots

Abstract

We propose and analyze a new method for manipulation of a heavy hole spin in a quantum dot. Due to spin-orbit coupling between states with different orbital momenta and opposite spin orientations, an applied rf electric field induces transitions between spin-up and spin-down states. This scheme can be used for detection of heavy-hole spin resonance signals, for the control of the spin dynamics in two-dimensional systems, and for determining important parameters of heavy-holes such as the effective g-factor, mass, spin-orbit coupling constants, spin relaxation and decoherence times.PACS numbers: 67.57. Lm,76.60.Es,73.21.La Spintronics, or spin-based electronics, is one of the fascinating and rapidly growing areas in solid state physics and modern technology [1]. Exploiting both the charge and spin degrees of freedom of carriers, it offers wide opportunities for developing devices with unique functionalities. Operation of single charge or spin is the ultimate limit for such devices. Quantum dots (QD) have proven useful for this goal [2], since experiments on readout and coherent manipulation of a single spin in QDs have already been performed successfully [3,4,5,6]. Furthermore, due to supression of the spin-orbit interaction (SOI) in QDs [7,8,9], the electron spin in a QD has long relaxation times T 1 (up to hundreds of milliseconds) [3,4,10]. The spin thus is an attractive candidate as carrier of quantum information [2], if its state stays coherent over sufficiently long times (described by the spin decoherence time T 2 ). At low magnetic fields, in III-V semiconductor QDs there is a rather strong hyperfine interaction between an electron spin and surrounding nuclear spins leading to a significant degradation of the spin coherence [11,12,13]. Very recently, based on the idea of state narrowing via projective measurements [13], several proposals have been made to limit the hyperfine-induced decoherence [14,15], and, therefore, to increase T 2 times for electron spins in QDs, which currently range up to µs [5,6].Electron spin resonance (ESR) provides a powerful tool for coherent manipulation of spins, which is of great importance for spintronics [16]. By applying short resonant microwave pulses, an arbitrary superposition of spin-up and spin-down states is created. Rabi oscillations and spin-echo experiments are based on this approach [5]. In such experiments, the ESR signal can be detected directly by measuring the absorption of radio-frequency (rf) power [16] via charge transport through a QD [6,17] or by using optical detection of magnetic resonance techniques [18,19]. Usually, ESR methods involve magnetic dipole transitions induced by an oscillating magnetic field. However, there has been a strong revival of interest in electric dipole spin resonance (EDSR) controlled by alternating electric fields [20,21,22,23,24,25] that provides the ability to manipulate and detect electron spins at the nanometer scale and may be useful for distinguishing different SOI mechanisms.Recently, the idea to use heavy-hole (HH)...

Understanding spin Hall effect in two-dimensional fermionic systems with generic spin–orbit interaction in III–V heterostructures

“…When l = 1, the Hamiltonian represents two dimensional electron gas with the k-linear Rashba 28,29 or Dresselhaus spin-orbit interaction 30 . The spin-orbit interaction corresponding to l = 2 arises when an in-plane magnetic field is applied to the 2D heavy hole gas 27,31,32 formed at the GaAs heterojunctions. In this case the spin-orbit coupling constant varies linearly with the applied magnetic field i.e.…”

Spin-Orbit-Mediated Manipulation of Heavy-Hole Spin Qubits in Gated Semiconductor Nanodevices

“…Not only long coherence times but also the possibility to initialize the hole spin state even without a magnetic field [25], and the recent realization of a coherent control of a hole spin state in single and double coupled quantum dots [32][33][34] has promoted the hole as a very good candidate as carrier of quantum bit information. There are also a few theoretical proposals how the HH spin state can be manipulated [35][36][37].In this paper we demonstrate by using a four band HH-LH model that the motion of the valence hole in gated semiconductor nanostructures can induce the rotation of the HH spin in the presence of the Dresselhaus spin-orbit interaction (DSOI). Supported by these results we present an efficient scheme which can be used to realize any rotation of the HH spin and propose a nanodevice which acts as a quantum logic NOT gate on a HH spin qubit.…”

“…Not only long coherence times but also the possibility to initialize the hole spin state even without a magnetic field [25], and the recent realization of a coherent control of a hole spin state in single and double coupled quantum dots [32][33][34] has promoted the hole as a very good candidate as carrier of quantum bit information. There are also a few theoretical proposals how the HH spin state can be manipulated [35][36][37].…”

Maximizing the purity of a qubit evolving in an anisotropic environment

“…45,46 In addition to optical coherent control of hole spins in self-assembled quantum dots, 39,41,47,48 there are several suggestions for electrical manipulation of hole spins. [49][50][51] Such electrical control has recently been demonstrated for hole spins in III-V nanowire quantum dots, 52 and coherence times have now been measured for hole spins in Ge-Si core-shell nanowire quantum dots. 53 The very recent achievement of the few-hole regime in lateral gated double-dot devices, 54 suggests that previous highly successful measurements performed for electron spins [55][56][57][58][59][60] can now be performed for hole spins, which show promise for much longer coherence times.…”