Spin-Orbit Coupling, Quantum Dots, and Qubits in Monolayer Transition Metal Dichalcogenides

Kormányos, Andor; Zólyomi, Viktor; Drummond, Neil; Burkard, Guido

doi:10.1103/physrevx.4.011034

Cited by 312 publications

(364 citation statements)

References 70 publications

(104 reference statements)

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“…4d). This assignment is mainly based on the fact that the extracted energy difference between the doublet is B25 meV, which agrees well with MoSe 2 conduction band splitting predicted by first-principle calculations 28 . This explanation is also supported by the evolution of the relative strength of the two peaks with increasing excitation power, as shown in Fig.…”

Section: Discussionsupporting

confidence: 70%

Observation of long-lived interlayer excitons in monolayer MoSe2–WSe2 heterostructures

et al. 2015

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Van der Waals bound heterostructures constructed with two-dimensional materials, such as graphene, boron nitride and transition metal dichalcogenides, have sparked wide interest in device physics and technologies at the two-dimensional limit. One highly coveted heterostructure is that of differing monolayer transition metal dichalcogenides with type-II band alignment, with bound electrons and holes localized in individual monolayers, that is, interlayer excitons. Here, we report the observation of interlayer excitons in monolayer MoSe 2 -WSe 2 heterostructures by photoluminescence and photoluminescence excitation spectroscopy. We find that their energy and luminescence intensity are highly tunable by an applied vertical gate voltage. Moreover, we measure an interlayer exciton lifetime of B1.8 ns, an order of magnitude longer than intralayer excitons in monolayers. Our work demonstrates optical pumping of interlayer electric polarization, which may provoke further exploration of interlayer exciton condensation, as well as new applications in two-dimensional lasers, light-emitting diodes and photovoltaic devices.

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Section: Discussionsupporting

confidence: 70%

Observation of long-lived interlayer excitons in monolayer MoSe2–WSe2 heterostructures

et al. 2015

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“…This magnetic moment is inherently coupled with the nuclear spins of the crystal lattice via OHF; therefore, if an electron is confined in a QD in these materials [57,58], then its operation as a valley qubit or as a spin-valley qubit will be influenced by the OHF-induced nuclear-spin-electron-valley interaction in a similar fashion as in a CNT. The OHF and its consequences in such two-dimensional materials have yet to be explored.…”

Section: Discussionmentioning

confidence: 99%

Orbital hyperfine interaction and qubit dephasing in carbon nanotube quantum dots

Csiszár

Pályi

2014

Phys. Rev. B

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Hyperfine interaction (HF) is of key importance for the functionality of solid-state quantum information processing, as it affects qubit coherence and enables nuclear-spin quantum memories. In this work, we complete the theory of the basic HF mechanisms (Fermi contact, dipolar, orbital) in carbon nanotube quantum dots by providing a theoretical description of the orbital HF. We find that orbital HF induces an interaction between the nuclear spins of the nanotube lattice and the valley degree of freedom of the electrons confined in the quantum dot. We show that the resulting nuclear-spin-electron-valley interaction (i) is approximately of Ising type; (ii) is essentially local, in the sense that a radius-and dot-length-independent atomic interaction strength can be defined; and (iii) has an atomic interaction strength that is comparable to the combined strength of the Fermi contact and dipolar interactions. We argue that orbital HF provides a new decoherence mechanism for single-electron valley qubits and spin-valley qubits in a range of multivalley materials. We explicitly evaluate the corresponding inhomogeneous dephasing time T * 2 for a nanotube-based valley qubit.

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“…These developments have culminated in demonstrations of optical writing and readout of spin states in single or coupled QDs [13][14][15][16][17]27]. While transition metal dichalcogenide monolayers (TMDs) with large exciton binding energies have been shown to emit single photons [28][29][30], we are not aware of any experimental demonstrations of qubit operations despite recent theoretical analysis [31].…”

Section: Introductionmentioning

confidence: 99%

Charge and spin control of ultrafast electron and hole dynamics in single CdSe/ZnSe quantum dots

et al. 2018

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We study the dynamics of photoexcited electrons and holes in single negatively charged CdSe/ZnSe quantum dots with two-color femtosecond pump-probe spectroscopy. An initial characterization of the energy level structure is performed at low temperatures and magnetic fields of up to 5 T. Emission and absorption resonances are assigned to specific transitions between few-fermion states by a theoretical model based on a configuration interaction approach. To analyze the dynamics of individual charge carriers, we initialize the quantum system into excited trion states with defined energy and spin. Subsequently, the time-dependent occupation of the trion ground state is monitored by spectrally resolved differential transmission measurements. We observe subpicosecond dynamics for a hole excited to the D shell. The energy dependence of this D-to-S shell intraband transition is investigated in quantum dots of varying size. Excitation of an electron-hole pair in the respective p shells leads to the formation of singlet and triplet spin configurations. Relaxation of the p-shell singlet is observed to occur on a time scale of a few picoseconds. Pumping of p-shell triplet transitions opens up two pathways with distinctly different scattering times. These processes are shown to be governed by the mixing of singlet and triplet states due to exchange interactions enabling simultaneous electron and hole spin flips. To isolate the relaxation channels, we align the spin of the residual electron by a magnetic field and employ laser pulses of defined helicity. This step provides ultrafast preparation of a fully inverted trion ground state of the quantum dot with near unity probability, enabling deterministic addition of a single photon to the probe pulse. Therefore our experiments represent a significant step towards using single quantum emitters with well-controled inversion to manipulate the photon statistics of ultrafast light pulses.

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Spin-Orbit Coupling, Quantum Dots, and Qubits in Monolayer Transition Metal Dichalcogenides

Cited by 312 publications

References 70 publications

Observation of long-lived interlayer excitons in monolayer MoSe2–WSe2 heterostructures

Observation of long-lived interlayer excitons in monolayer MoSe2–WSe2 heterostructures

Orbital hyperfine interaction and qubit dephasing in carbon nanotube quantum dots

Charge and spin control of ultrafast electron and hole dynamics in single CdSe/ZnSe quantum dots

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