Electron-spin-resonance transistors for quantum computing in silicon-germanium heterostructures

Vrijen, R. B.; Yablonovitch, Eli; Wang, Kang; Jiang, Hongda; Balandin, A.A.; Roychowdhury, Vwani P.; Mor, Tal; DiVincenzo, David P.

doi:10.1103/physreva.62.012306

Cited by 817 publications

(803 citation statements)

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“…We propose a phenomenological model for the change in g-factor based on resonant changes in the amplitude of the wavefunction in the barrier due to the formation of bonding and antibonding orbitals. Quantum Dots and Quantum Dot Molecules (QDMs) have proven to be a versatile medium for isolating and manipulating spins [1,2], which are of great interest for quantum information processing [3,4]. In particular, photoluminescence (PL) spectra have been used in self-assembled QDMs to observe coherent tunneling [5,6,7,8] and identify spin interactions through fine structure [9].…”

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confidence: 99%

Electrically TunablegFactors in Quantum Dot Molecular Spin States

et al. 2006

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We present a magneto-photoluminescence study of individual vertically stacked InAs/GaAs quantum dot pairs separated by thin tunnel barriers. As an applied electric field tunes the relative energies of the two dots, we observe a strong resonant increase or decrease in the g-factors of different spin states that have molecular wavefunctions distributed over both quantum dots. We propose a phenomenological model for the change in g-factor based on resonant changes in the amplitude of the wavefunction in the barrier due to the formation of bonding and antibonding orbitals. PACS numbers: 75.40.Gb, 78.20.Ls, 78.47.+p, 78.67.Hc Quantum Dots and Quantum Dot Molecules (QDMs) have proven to be a versatile medium for isolating and manipulating spins [1,2], which are of great interest for quantum information processing [3,4]. In particular, photoluminescence (PL) spectra have been used in self-assembled QDMs to observe coherent tunneling [5,6,7,8] and identify spin interactions through fine structure [9]. Electrical control of isolated spins through their g-factors is highly desireable for implementation of quantum gate operations. To date, electrical control of g-factors has only been observed in ensembles of electrons in quantum wells by shifting the electron wavefunctions into different materials [10,11,12,13]. In this Letter we present a striking electric field resonance in the g-factor for molecular spin states confined to a single quantum dot molecule.To our knowledge this is the first observation of electrical control over the g-factor for a single confined spin. Moreover, the isolation of a single QDM allows us to spectrally resolve and identify individual molecular spin states that have different g-factor behaviors. In Fig. 1a we indicate molecular spin states of both the neutral exciton (X 0 , one electron recombining with one hole) and positive trion (X + , electron-hole recombination in the presence of an extra hole) at zero magnetic field. The different electric field dependences of the g-factors for these states is apparent in Fig. 1b, where the splitting of PL lines increases for some molecular spin states and decreases for others. This electric field dependence is nearly an order of magnitude larger than previously reported in quantum wells [10,11,12,13]. The effect arises from the formation of bonding and antibonding orbitals, which results in a change in the amplitude of the wavefunction in the barrier at resonance.Our QDMs consist of two vertically stacked selfassembled InAs dots truncated at a thickness of 2.5 nm and separated by a 2 nm GaAs tunneling barrier [14]. As an applied electric field tunes the relative energies of the two dots, strong tunnel coupling between the hole states creates the molecular spin states. Unlike samples with a thicker tunnel barrier [5], the states retain molecular character throughout the observed range of electric fields. We present data from a single molecule, but the universality of the behavior has been verified by detailed studies of 7 other molecules from the same ...

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confidence: 99%

Electrically TunablegFactors in Quantum Dot Molecular Spin States

et al. 2006

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“…We remark that the Bloch phases interference behavior in the donor wavefunctions are well captured in the TB wavefunctions, and that the results above demonstrate that electric field control over single donor wavefunctions, such as proposed in A-gate operations, (Kane 1998, Vrijen et al 2000, Skinner et al 2003 do not present additional complications due to the Si band structure. The only critical parameter is the donor positioning below the Si/barrier interface, which should be chosen and controlled according to physical criteria such as those discussed here.…”

Section: Electric-field Control Of Shallow Donor In Siliconmentioning

confidence: 72%

“…The A-gate (according to the nomenclature originally proposed by Kane 1998), placed above each donor site, pulls the electron wavefunction away from the donor, aiming at partial reduction (Kane 1998) or total cancellation (Skinner et al 2003) of the electron-nuclear hyperfine coupling in architectures where the qubits are the 31 P nuclear spins. In a related proposal based on the donor electron spins as qubits (Vrijen et al 2000), the gates drive the electron wavefunction into regions of different g-factors, allowing the exchange coupling between neighboring electrons to be tuned.…”

Section: Electric-field Control Of Shallow Donor In Siliconmentioning

confidence: 99%

“…Among the more prominent solid state examples are electron or nuclear spins in semiconductors (Žutić et al 2004, Das Sarma et al 2001, Hu 2004, Das Sarma et al 2005, including electron spin in semiconductor quantum dots (Loss andDiVincenzo 1998, Imamoglu et al 1999) and donor electron or nuclear spins in semiconductors (Kane 1998, Vrijen et al 2000.…”

Section: Introductionmentioning

confidence: 99%

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Silicon-based spin and charge quantum computation

Koiller

Capaz

et al. 2005

An. Acad. Bras. Ciênc.

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Silicon-based quantum-computer architectures have attracted attention because of their promise for scalability and their potential for synergetically utilizing the available resources associated with the existing Si technology infrastructure. Electronic and nuclear spins of shallow donors (e.g. phosphorus) in Si are ideal candidates for qubits in such proposals due to the relatively long spin coherence times. For these spin qubits, donor electron charge manipulation by external gates is a key ingredient for control and read-out of single-qubit operations, while shallow donor exchange gates are frequently invoked to perform two-qubit operations. More recently, charge qubits based on tunnel coupling in P + 2 substitutional molecular ions in Si have also been proposed. We discuss the feasibility of the building blocks involved in shallow donor quantum computation in silicon, taking into account the peculiarities of silicon electronic structure, in particular the six degenerate states at the conduction band edge. We show that quantum interference among these states does not significantly affect operations involving a single donor, but leads to fast oscillations in electron exchange coupling and on tunnel-coupling strength when the donor pair relative position is changed on a lattice-parameter scale. These studies illustrate the considerable potential as well as the tremendous challenges posed by donor spin and charge as candidates for qubits in silicon.Key words: semiconductors, quantum computation, nanoelectronic devices, spintronics, nanofabrication, donors in silicon.

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“…Because this silicon isotope has zero nuclear spin, the spin-1/2 phosphorous atom is ideally isolated from other spin contaminants [17]. Several works that followed the Kane proposal have also outlined how to realize qubits using the unpaired donor-bound electron, opening up the potential for easier addressability and faster gate operation [10,[18][19][20]. Recent experiments using isotopically purified 28 Si have demonstrated single-qubit coherence times (T 2 ) over 30 s (nuclear spin) and 0.5 s (electron spin) at cryogenic temperatures [9].…”

Section: Silicon Donor Qubit Modelsmentioning

confidence: 99%

A computational workflow for designing silicon donor qubits

et al. 2016

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Developing devices that can reliably and accurately demonstrate the principles of superposition and entanglement is an on-going challenge for the quantum computing community. Modeling and simulation offer attractive means of testing early device designs and establishing expectations for operational performance. However, the complex integrated material systems required by quantum device designs are not captured by any single existing computational modeling method. We examine the development and analysis of a multi-staged computational workflow that can be used to design and characterize silicon donor qubit systems with modeling and simulation. Our approach integrates quantum chemistry calculations with electrostatic field solvers to perform detailed simulations of a phosphorus dopant in silicon. We show how atomistic details can be synthesized into an operational model for the logical gates that define quantum computation in this particular technology. The resulting computational workflow realizes a design tool for silicon donor qubits that can help verify and validate current and nearterm experimental devices.

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Electron-spin-resonance transistors for quantum computing in silicon-germanium heterostructures

Cited by 817 publications

References 31 publications

Electrically TunablegFactors in Quantum Dot Molecular Spin States

Electrically TunablegFactors in Quantum Dot Molecular Spin States

Silicon-based spin and charge quantum computation

A computational workflow for designing silicon donor qubits

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