Nuclear magnetic resonance inverse spectra of InGaAs quantum dots: Atomistic level structural information

Bulutay, Ceyhun; Chekhovich, E. A.; Tartakovskii, A. I.

doi:10.1103/physrevb.90.205425

Cited by 24 publications

(45 citation statements)

References 42 publications

(58 reference statements)

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“…In their analysis, as a proof of principle they have considered a simple QI Hamiltonian neglecting the biaxiality (η) of the electric field gradient (EFG). In nanostructures such as semiconductor quantum dots, the biaxiality of the EFG is quite pronounced [47,48]. Its presence, as we shall show, offers the opportunity to combine both OAT and TAC models.…”

Section: Introductionmentioning

confidence: 99%

“…This results in the coupling of the nuclear spin to the so-called electric field gradient (EFG), if available at that nuclear site. In a solid-state context, one common cause of EFG is the crystal electric fields of polar group III-V semiconductor quantum dots under inhomogeneous strain [47,48]. The elements of the EFG tensor can be given by the Cartesian second derivatives of the (crystal) electric potential as,…”

Section: Theory a Electric Quadrupole Interactionmentioning

confidence: 99%

“…The key parameter in this context is the strength of the QI as characterized by the quadrupolar frequency. Typically this ranges from 10 kHz in lyotropic samples [46] to a few MHz in self-assembled quantum dots [47,48]. Based on these, one can estimate the squeezing times to be on the order between 1-100 µs.…”

Section: Introductionmentioning

confidence: 99%

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Nuclear spin squeezing via electric quadrupole interaction

Korkmaz

Bulutay

2016

Phys. Rev. A

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Control over nuclear spin fluctuations is essential for processes that rely on preserving the quantum state of an embedded system. For this purpose, squeezing is a viable alternative, so far that has not been properly exploited for the nuclear spins. Of particular relevance in solids is the electric quadrupole interaction (QI), which operates on nuclei having spin higher than 1/2. In its general form, QI involves an electric field gradient (EFG) biaxiality term. Here, we show that as this EFG biaxiality increases, it enables continuous tuning of single-particle squeezing from the one-axis twisting to the two-axis countertwisting limits. A detailed analysis of QI squeezing is provided, exhibiting the intricate consequences of EFG biaxiality. The initial states over the Bloch sphere are mapped out to identify those favorable for fast initial squeezing, or for prolonged squeezings. Furthermore, the evolution of squeezing in the presence of a phase-damping channel and an external magnetic field are investigated. We observe that dephasing drives toward an anti-squeezed terminal state, the degree of which increases with the spin angular momentum. Finally, QI squeezing in the limiting case of a two-dimensional EFG with a perpendicular magnetic field is discussed, which is of importance for two-dimensional materials, and the associated beat patterns in squeezing are revealed.

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Section: Introductionmentioning

confidence: 99%

Section: Theory a Electric Quadrupole Interactionmentioning

confidence: 99%

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Nuclear spin squeezing via electric quadrupole interaction

Korkmaz

Bulutay

2016

Phys. Rev. A

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“…In the literature, exclusively the spin-1/2 NSB has been treated [3-7, 9, 16-19], and sometimes indirectly through the so-called pseudospin approximation [22], despite the fact that group III-V semiconductors involve quadrupolar nuclei, where I ≥ 1 [27]. Therefore, we extend our consideration to the nuclear electric quadrupole interaction (QI) practically resulting from the atomistic strain in semiconductor structures for the case of quadrupolar NSB [28,29]. We identify under what circumstances and how the action of QI on LE becomes significant.…”

Section: Introductionmentioning

confidence: 99%

Loschmidt echo driven by hyperfine and electric-quadrupole interactions in nanoscale nuclear spin baths

Güldeste

Bulutay

2018

Phys. Rev. B

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The nuclear spin bath (NSB) dynamics and its quantum control are of importance for the storage and processing of quantum information within a semiconductor environment. In the presence of a carrier spin, primarily it is the hyperfine interaction that rules the high frequency NSB characteristics. Here, we first study the overall coherence decay and rephasings in a hyperfine-driven NSB through the temporal and spectral behaviors of the so-called Loschmidt echo (LE). Its dependence on the NSB size, initial polarization, and coupling inhomogeneity are separately investigated, which leads to a simple phenomenological expression that can accommodate all of these attributes. Unlike the prevailing emphasis on spin 1/2, the NSBs with larger spin quantum numbers are equally considered. For this case, additionally the effect of nuclear electric quadrupole interaction is taken into account where its biaxiality term is influential on the decoherence. The insights gained from model systems are then put to use for two generic realistic semiconductor systems, namely, a donor center and a quantum dot that represent small and large nanoscale NSB examples, respectively. The spectrum of LE for large quantum dots can reach the 100 MHz range, whereas, for donor centers, it reduces to a few MHz, making them readily amenable for dynamical decoupling techniques. The effect of quadrupole interaction on LE is seen to be negligible for large quantum dots, while it becomes significant for donor centers, most notably in the form of depolarizing a polarized NSB.

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“…However, macroscopic samples are needed for the conventional NMR detection technique to work. Furthermore, it is difficult to get information of the electronexisting nanometer scale area inside the semiconductors with these techniques.To overcome the limitation, the so-called opticallydetected (or optically-pumped) NMR with quadrupole nuclei has been developed and exploited intensively to investigate structural information of strained semiconductor nanostructures [17][18][19][20][21][22][23][24][25][26]. However this technique requires an interrogated structure to be optically accessible, which cannot be easily applied to nanostructure transport devices defined by surface gate metals such as quantum point contacts [5,6] or lateral surface superlattices [27][28][29].…”

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confidence: 99%

Probing strain modulation in a gate-defined one-dimensional electron system

et al. 2019

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Gate patterning on semiconductors is routinely used to electrostatically restrict electron movement into reduced dimensions. At cryogenic temperatures, where most studies are carried out, differential thermal contraction between the patterned gate and the semiconductor often lead to an appreciable strain modulation. The impact of such modulated strain to the conductive channel buried in a semiconductor has long been recognized, but measuring its magnitude and variation is rather challenging. Here we present a way to measure that modulation in a gate-defined GaAs-based onedimensional channel by applying resistively-detected NMR (RDNMR) with in-situ electrons coupled to quadrupole nuclei. The detected strain magnitude, deduced from the quadrupole-split resonance, varies spatially on the order of 10 −4 , which is consistent with the predicted variation based on an elastic strain model. We estimate the initial lateral strain xx developed at the interface to be about 3.5 × 10 −3 .In many semiconductor-based quantum systems, electrons are manipulated by applying voltages to the surface metal gates. For example, a combination of nanoscale metal gates and GaAs based two-dimensional systems enables us to realize one-dimensional quantum channel and zero-dimensional quantum dot by depleting electrons under the gates[1]. These building blocks are integrated into many quantum devices, such as quantum computing/simulating systems based on electron spins [2][3][4]. Electron control in these systems is always accompanied by electron position change from the originally twodimensional sheet. One can expect microscopic strain distribution in such devices because surface metal gate and semiconductor system have different thermal expansion coefficients and complicated nanometer surface gates should produce a complicated strain pattern inside. Such phenomena are common for all semiconductor systems including silicon and other semiconductor groups. However, the strain variation felt by confined electrons has not received much attention up to now partly because a lack of appropriate and precise measurement tool to probe local strain in nanometer scale electron channel. Here, taking GaAs-based quantum-point-contact (QPC)[5, 6] as a prototypical example, we demonstrate that electrons flowing in the one-dimensional channel feel different strain even in the same device when the channel position is microscopically shifted by changing the gate voltage.There are a couple of methods to measure spatial strain distribution in materials. Examples include X-ray diffraction [7,8], electron microscopy [9,10], and Raman spectroscopy [11][12][13]. Although those techniques are capable of delivering a high-spatial resolution strain profile, they are only sensitive to strain magnitude larger than a factor of 10 −4 . Alternative technique such as solidstate NMR could provide an acceptable solution since it has the ability to detect ultra low-level strain variation of less than 10 −4 through nuclear quadrupolar interaction with the electric field gradient ...

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Nuclear magnetic resonance inverse spectra of InGaAs quantum dots: Atomistic level structural information

Cited by 24 publications

References 42 publications

Nuclear spin squeezing via electric quadrupole interaction

Nuclear spin squeezing via electric quadrupole interaction

Loschmidt echo driven by hyperfine and electric-quadrupole interactions in nanoscale nuclear spin baths

Probing strain modulation in a gate-defined one-dimensional electron system

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