Optical Spin Initialization and Nondestructive Measurement in a Quantum Dot Molecule

Kim, Danny; Economou, Sophia E.; Bădescu, Ştefan C.; Scheibner, Michael; Bracker, Allan S.; Bashkansky, Mark; Reinecke, T. L.; Gammon, D.

doi:10.1103/physrevlett.101.236804

Cited by 89 publications

(77 citation statements)

References 37 publications

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“…8 The transverse magnetic field prevents nondestructive readout. 9 A third obstacle is the suppression of decoherence. Among the many channels for decoherence, the hyperfine interaction with nuclei is the most detrimental.…”

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confidence: 99%

“…1 Spins confined in III-V semiconductor self-assembled quantum dots (QDs) have received a great deal of attention because they interact strongly with light and provide the opportunity for ultrafast all-optical implementation of logic operations. [2][3][4][5] There has been dramatic progress in the initialization, coherent manipulation and readout of single spins in GaAs and InGaAs QDs, [6][7][8][9][10][11][12][13] but many challenges to the creation of a scalable quantum logic device based on optical control of single spins remain. One serious obstacle is the natural inhomogeneous distribution of energy levels in a quantum dot ensemble.…”

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confidence: 99%

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Scalable qubit architecture based on holes in quantum dot molecules

et al. 2012

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Spins confined in quantum dots are a leading candidate for solid-state quantum bits that can be coherently controlled by optical pulses. There are, however, many challenges to developing a scalable multibit information processing device based on spins in quantum dots, including the natural inhomogeneous distribution of quantum dot energy levels, the difficulty of creating all-optical spin manipulation protocols compatible with nondestructive readout, and the substantial electron-nuclear hyperfine interaction-induced decoherence. Here, we present a scalable qubit design and device architecture based on the spin states of single holes confined in a quantum dot molecule. The quantum dot molecule qubit enables a new strategy for optical coherent control with dramatically enhanced wavelength tunability. The use of hole spins allows the suppression of decoherence via hyperfine interactions and enables coherent spin rotations using Raman transitions mediated by a hole-spin-mixed optically excited state. Because the spin mixing is present only in the optically excited state, dephasing and decoherence are strongly suppressed in the ground states that define the qubits and nondestructive readout is possible. We present the qubit and device designs and analyze the wavelength tunability and fidelity of gate operations that can be implemented using this strategy. We then present experimental and theoretical progress toward implementing this design.Comment: 13 pages, 9 figure

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Scalable qubit architecture based on holes in quantum dot molecules

et al. 2012

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“…for non-destructive spin readout measurements via cycling transitions. [15] By contrast, p-shell excitations to the hot trion are no longer as spin selective as in negative trions. [2] The large spin mixing renders optically active otherwise dark trion states, e.g.…”

Section: Hot Trionmentioning

confidence: 99%

“…Circular dots are not only of fundamental interest -realistic self-assembled QDs often present but small deviations from this ideal limit-, but also of practical importance, as highly symmetric QDs are desirable for spintronic applications to minimize spin admixture through spin-orbit interaction. [13,14,15] Holes are described as Luttinger spinors resulting from a 4-band k·p Hamiltonian. We find that HH-LH coupling gives rise to large splittings of the p-shell even if the QDs have perfect circular symmetry, and show that this follows from the unequal centrifugal energy of the minor components in p + and p − states.…”

Section: Introductionmentioning

confidence: 99%

Origin of two-hole triplet splitting in circular quantum dots

Climente

2012

Solid State Communications

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Recent photoluminescence spectra of positively charged excitons in InAs/GaAs quantum dots have revealed the existence of large splittings between the pshell triplet sublevels of holes. We provide an intuitive explanation for their origin in terms of heavy hole-light hole coupling using Luttinger spinors. These splittings are present even in symmetric quantum dots at zero field and their magnitude can be tuned by the geometry of the dot. We show that the spin purity of the triplet drastically decreases with the aspect ratio, but that of the singlet ground state remains high.

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“…Recently, there have been a number of breakthroughs. Continuous-wave pumping schemes for the high-fidelity preparation of an electron [20], and hole [21] spin have been demonstrated, not only in a Faraday geometry B-field, but also for electron spins in the Voigt geometry B-field needed for optical control [22,23]. Recently, partial [24,25], and full [26] optical control of a single electron spin has been demonstrated.…”

Section: Introductionmentioning

confidence: 99%

Towards coherent optical control of a single hole spin: Rabi rotation of a trion conditional on the spin state of the hole

Ramsay¹,

Boyle²,

Godden³

et al. 2009

Solid State Communications

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A hole spin is a potential solid-state q-bit, that may be more robust against nuclear spin induced dephasing than an electron spin. Here we propose and demonstrate the sequential preparation, control and detection of a single hole spin trapped on a self-assembled InGaAs/GaAs quantum dot. The dot is embedded in a photodiode structure under an applied electric-field. Fast, triggered, initialization of a hole spin is achieved by creating a spin-polarized electron-hole pair with a picosecond laser pulse, and in an applied electricfield, waiting for the electron to tunnel leaving a spin-polarized hole. Detection of the hole spin with picosecond time resolution is achieved a second picosecond laser pulse to probe the positive trion transition, where a trion is created conditional on the hole spin to be detected as a change in photocurrent. Finally, using this setup we observe a Rabi rotation of the hole-trion transition that is conditional on the hole spin, which for a pulse-area of 2π can be used to impart a phase-shift of π between the hole spin states, a non-general manipulation of the hole spin.

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Optical Spin Initialization and Nondestructive Measurement in a Quantum Dot Molecule

Cited by 89 publications

References 37 publications

Scalable qubit architecture based on holes in quantum dot molecules

Scalable qubit architecture based on holes in quantum dot molecules

Origin of two-hole triplet splitting in circular quantum dots

Towards coherent optical control of a single hole spin: Rabi rotation of a trion conditional on the spin state of the hole

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