Exciton states in shallow ZnSe/(Zn,Mg)Se quantum wells: Interaction of confined and continuum electron and hole states

Pawlis, A.; Berstermann, T.; Brüggemann, Christian; Bombeck, M.; Dunker, D.; Yakovlev, D. R.; Gippius, N. A.; Lischka, K.; Bayer, М.

doi:10.1103/physrevb.83.115302

Cited by 27 publications

(19 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…28 Furthermore, this approach is strictly limited to (Al,Ga)As-based systems and cannot be extended to other material system (e.g. II/VI) 29,30 . Also, it cannot be simply extended to two-electron spin qubits with singlet-triplet encoding, which have the advantage of full electrical control.…”

Section: A Transfer Protocolmentioning

confidence: 99%

Transfer of a quantum state from a photonic qubit to a gate-defined quantum dot

et al. 2019

View full text Add to dashboard Cite

Interconnecting well-functioning, scalable stationary qubits and photonic qubits could substantially advance quantum communication applications and serve to link future quantum processors. Here, we present two protocols for transferring the state of a photonic qubit to a single-spin and to a two-spin qubit hosted in gate-defined quantum dots (GDQD). Both protocols are based on using a localized exciton as intermediary between the photonic and the spin qubit. We use effective Hamiltonian models to describe the hybrid systems formed by the the exciton and the GDQDs and apply simple but realistic noise models to analyze the viability of the proposed protocols. Using realistic parameters, we find that the protocols can be completed with a success probability ranging between 85-97 %. I. INTODUCTIONSemiconductor quantum-dot devices have demonstrated considerable potential for quantum information applications. A prominent example are gate-defined quantum dots (GDQD), i.e. quantum dots realized in semiconductor heterostructures in which individual electrons are confined by an electrostatic trapping potential. Spin qubits based on GDQD in GaAs/Al x Ga x−1 As heterostructures have demonstrated all key requirements for quantum information processing, such as qubit initialization, readout, 1,2 coherent control 3,4 with high fidelity 5,6 and two-qubit gates. 7,8 Moreover, thanks to their similarity to the transistors used in modern computer chips, these top-down fabricated quantum dots have good prospects for realizing large scale quantum processing nodes. However, unlike self-assembled quantum dots, where excellent optical control and information transfer has been demonstrated, [9][10][11] GDQDs pose a number of challenges when it comes to couple them coherently with light. The problems come from the lack of exciton confinement: while the electron states are confined, the hole states are not. Since in the creation of an exciton the spin of the photo-excited electron is always entangled with the one of the hole, discarding the hole-spin inevitably leads to decoherence of the electron spin. This limits considerably the possibility of optically controlling and manipulating spins in GDQDs, and it hinders their applicability in quantum communications.Despite these difficulties, first steps towards the goal of coherently coupling photons and electron spins in GDQDs have already been made, by trapping and detecting photo-generated carriers in GDQDs, 12 and by proving transfer of angular momentum between photons and electrons. 13 Much of this effort is motivated by the fact that robust spin-photon entanglement is a key requirement for quantum repeaters for long-distance quantum communications, 14 as well as for distributed quantum computing, where different computing nodes based on GDQD are connected by optical channels. 15 One strategy to avoid entanglement between the spins of the electron and the hole is to use g-factor engineering to obtain a much smaller g-factor for the electrons than for holes. [16][17][18] Here we propose a ...

show abstract

Section: A Transfer Protocolmentioning

confidence: 99%

Transfer of a quantum state from a photonic qubit to a gate-defined quantum dot

et al. 2019

View full text Add to dashboard Cite

show abstract

“…The first one is a homogeneous spin system based on a ZnSe epilayer doped with fluorine donors. In this system, resident electrons are bound on the donors which results in a strong localization of electrons . Due to localization a long electron spin coherence time in a transverse magnetic field is present in the systems.…”

Section: Estimations Of the Maximal Overhauser Field For The Differenmentioning

confidence: 99%

Theoretical Modeling of the Nuclear‐Field Induced Tuning of the Electron Spin Precession for Localized Spins

Kopteva

Yugova

Zhukov

et al. 2019

Physica Status Solidi (b)

View full text Add to dashboard Cite

This work is devoted to a theoretical analysis of the effect of nuclear-induced field (Overhauser field) on the Larmor frequencies of electron spins under the periodic pulsed excitation. To describe the dynamical nuclear spin polarization, we use the model where the optically induced Stark field determines the magnitude and direction of the Overhauser field. The Stark field strongly depends on the detuning between the photon energy of excitation and the optical transition energy in the quantum system. Detailed calculations which show that the precession frequencies of fluorine donorbound electron spins in ZnSe deviate from the linear dependence of the Larmor frequencies on the external magnetic field have been performed. A similar effect is observed for the (In,Ga)As/GaAs quantum dots, where it has been shown that the Overhauser field strongly changes the spectrum of the electron spin precession frequencies.

show abstract

“…The general parameters we used for modeling the ZnSe and (Zn,Mg)Se are the same as in Ref. [36] and the ternary material was linearly interpolated (Vegard's law).…”

Section: Model and Calculationsmentioning

confidence: 99%

“…Note that due to the complete parameter sets in Ref. [36] and Table II as well as the experimental information (magnesium concentration, ZnSe thickness, and CdSe QW width) no free parameter is remaining for any fitting of the calculated data with the measured peak energies.…”

Section: Model and Calculationsmentioning

confidence: 99%

Extending the spectral range of CdSe/ZnSe quantum wells by strain engineering

et al. 2015

Self Cite

View full text Add to dashboard Cite

We demonstrate efficient room-temperature photoluminescence and spectral tuning of epitaxially grown ZnSe/CdSe quantum well structures almost over the whole visible spectrum (470-600 nm wavelength). The key element to achieve the observed high quantum efficiency and enormous tuning range was the implementation of a special strain engineering technique, which allows us to suppress substantial lattice relaxation of CdSe on ZnSe. Previous studies indicated that a CdSe coverage exceeding 3 ML on ZnSe results in the formation of extensive lattice defects and complete quenching of the photoluminescence at low and room temperature. In contrast, our approach of strain engineering enables the deposition of planar CdSe quantum wells with a thickness ranging from 1 to 6 ML with excellent optical properties. We attribute the observed experimental features to a controllable strain compensation effect that is present in an alternating system of tensile and compressively strained epitaxial layers and supported this model by calculations of the transition energies of the ZnSe/CdSe quantum wells. PACS number(s): 85.60.−q, 71.20.Mq, 78.55.−m, 78.67.−n 1098-0121/2015/91(3)/035409(8) 035409-1

show abstract

Exciton states in shallow ZnSe/(Zn,Mg)Se quantum wells: Interaction of confined and continuum electron and hole states

Cited by 27 publications

References 28 publications

Transfer of a quantum state from a photonic qubit to a gate-defined quantum dot

Transfer of a quantum state from a photonic qubit to a gate-defined quantum dot

Theoretical Modeling of the Nuclear‐Field Induced Tuning of the Electron Spin Precession for Localized Spins

Extending the spectral range of CdSe/ZnSe quantum wells by strain engineering

Contact Info

Product

Resources

About