Low-temperature magnetic susceptibility of Si: P in the nonmetallic region

Andres, K.; Bhatt, R. N.; Goalwin, P.; Rice, T. M.; Walstedt, R. E.

doi:10.1103/physrevb.24.244

Cited by 181 publications

(121 citation statements)

References 25 publications

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“…The exchange is modelled as Heisenberg (σ · σ) interactions. Although in Si the true exchange is complicated by the indirect nature of the bandgap, and consequent intervalley interference and anisotropic effective mass effects, Andres et al (1981) and Koiller et al (2002aKoiller et al ( , 2002b show that the characteristic strength of the exchange interaction between defects can be related to the 'hydrogenic' value (Slater 1963, Herring andFlicker 1964), and this is what we assume. Thus, as we show in figure 2, there is a range of separations for which exchange between the ground states of A, B and C is negligible, and for which exchange between the excited state of C and A and C and B is usefully large.…”

Section: The Interaction Hamiltonianmentioning

confidence: 99%

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Avoiding entanglement loss when two-qubit quantum gates are controlled by electronic excitation

Rodriquez

Fisher²,

Greenland³

et al. 2004

J. Phys.: Condens. Matter

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A solid-state two-qubit quantum gate was recently proposed that might be made in a silicon fabrication plant in the near future. In this class of device, entanglement between two quantum bits is controlled by a change from a largely unentangled ground electronic state to an excited state in which useful entanglement can be produced. Such gates have potential advantages, both because they exploit known solid-state behaviour and they separate the storage and manipulation of quantum information. It is important that the excitation step does not create decoherence. We analyse a type of gate proposed before, in which the excitation involves a control electron that interacts with the qubit spins in the excited state. The dynamics of an idealized (but fairly general) gate of this type show that it can be operated to produce a standard two-qubit entangling state.

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Section: The Interaction Hamiltonianmentioning

confidence: 99%

“…(At this separation the magnetic dipole-dipole interaction between the active electrons is ∼10 peV, and we ignore it.) Further details of exchange strengths in Si can be found in Herring and Flicker (1964), Cullis and Marko (1970), Stoneham (1975), Andres et al (1981), Koiller et al (2002aKoiller et al ( , 2002b.…”

Section: The Interaction Hamiltonianmentioning

confidence: 99%

Avoiding entanglement loss when two-qubit quantum gates are controlled by electronic excitation

Rodriquez

Fisher²,

Greenland³

et al. 2004

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

show abstract

“…Such control can presumably be achieved by fabrication of donor arrays with well-controlled positioning and surface gate potential (O'Brien et al 2001, Schofield et al 2003, Buehler et al 2002, Schenkel et al 2003. However, electron exchange in bulk silicon has spatial oscillations (Andres et al 1981, Koiller et al 2002 on the atomic scale due to valley interference arising from the particular six-fold degeneracy of the bulk Si conduction band. These exchange oscillations place heavy burdens on device fabrication and coherent control (Koiller et al 2002a), because of the very high accuracy and tolerance requirements for placing each donor inside the Si unit cell, and/or for controlling the external gate voltages.…”

Section: Electric-field Control Of Shallow Donor In Siliconmentioning

confidence: 99%

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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“…The effects of these properties have been considered elsewhere [16][17][18]. We have not estimated the overlap factors associated with the Bloch functions; these will give a factor that varies rapidly from one site to another, but the key analysis will not be affected [13,19].…”

Section: The Model Systemmentioning

confidence: 99%

Time dependent quantum simulations of two-qubit gates based on donor states in silicon

Kerridge¹,

Savory²,

Harker³

et al. 2006

J. Phys.: Condens. Matter

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Many quantum gate proposals make physical assumptions to ease analysis. Here we explicitly consider the effect of these assumptions for a particular two-qubit gate proposal, a cube-root-of-unity gate, in which the two qubits are donors in a semiconductor coupled via an intermediate 'control' spin. Our approach considers directly the electronic structures of the qubit and control impurity systems. We find that such gates are highly sensitive to environmental factors overlooked in analytically soluble models, but that there are regimes in which simplifying assumptions are valid and lead to high fidelity gates.

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Low-temperature magnetic susceptibility of Si: P in the nonmetallic region

Cited by 181 publications

References 25 publications

Avoiding entanglement loss when two-qubit quantum gates are controlled by electronic excitation

Avoiding entanglement loss when two-qubit quantum gates are controlled by electronic excitation

Silicon-based spin and charge quantum computation

Time dependent quantum simulations of two-qubit gates based on donor states in silicon

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