Surface code architecture for donors and dots in silicon with imprecise and nonuniform qubit couplings

Pica, Giuseppe; Lovett, Brendon W.; Bhatt, R. N.; Schenkel, T.; Lyon, S. A.

doi:10.1103/physrevb.93.035306

Cited by 64 publications

(106 citation statements)

References 50 publications

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“…Based on this, they presented a multi-valley effective-mass theory (MV-EMT) by explicitly including the central-cell correction along with a non-static dielectric screening of the Coulomb potential representing the donor. Similar EMT based formalisms have been widely applied by various studies later on to investigate the physics of shallow donors [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Donor hyperfine Stark shift and the role of central-cell corrections in tight-binding theory

Usman

Rahman

Salfi

et al. 2015

J. Phys.: Condens. Matter

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Atomistic tight-binding (TB) simulations are performed to calculate the Stark shift of the hyperfine coupling for a single Arsenic (As) donor in Silicon (Si). The role of the central-cell correction is studied by implementing both the static and the non-static dielectric screenings of the donor potential, and by including the effect of the lattice strain close to the donor site. The dielectric screening of the donor potential tunes the value of the quadratic Stark shift parameter (η2) from -1.3 × 10 −3 µm 2 /V 2 for the static dielectric screening to -1.72 × 10 −3 µm 2 /V 2 for the non-static dielectric screening. The effect of lattice strain, implemented by a 3.2% change in the As-Si nearest-neighbour bond length, further shifts the value of η2 to -1.87 × 10 −3 µm 2 /V 2 , resulting in an excellent agreement of theory with the experimentally measured value of -1.9 ± 0.2 × 10 −3 µm 2 /V 2 . Based on our direct comparison of the calculations with the experiment, we conclude that the previously ignored non-static dielectric screening of the donor potential and the lattice strain significantly influence the donor wave function charge density and thereby leads to a better agreement with the available experimental data sets.

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Section: Introductionmentioning

confidence: 99%

Donor hyperfine Stark shift and the role of central-cell corrections in tight-binding theory

Usman

Rahman

Salfi

et al. 2015

J. Phys.: Condens. Matter

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“…We choose this scope because it allows us to consider important near-term challenges for error correction using quantum dots; moreover, there are several proposals that provide good coverage of large-scale silicon-qubit designs in the longer term [1,2,5,[63][64][65][66]. Based on recent results in SiMOS dots [27,40,67], we design spin-control protocols and error-correction instruction sequences.…”

Section: Introductionmentioning

confidence: 99%

Logical Qubit in a Linear Array of Semiconductor Quantum Dots

et al. 2018

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We design a logical qubit consisting of a linear array of quantum dots, we analyze error correction for this linear architecture, and we propose a sequence of experiments to demonstrate components of the logical qubit on near-term devices. To avoid the difficulty of fully controlling a two-dimensional array of dots, we adapt spin control and error correction to a one-dimensional line of silicon quantum dots. Control speed and efficiency are maintained via a scheme in which electron spin states are controlled globally using broadband microwave pulses for magnetic resonance, while two-qubit gates are provided by local electrical control of the exchange interaction between neighboring dots. Error correction with two-, three-, and fourqubit codes is adapted to a linear chain of qubits with nearest-neighbor gates. We estimate an error correction threshold of 10 −4 . Furthermore, we describe a sequence of experiments to validate the methods on near-term devices starting from four coupled dots.

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“…This enables the rapid manipulation of two nearly degenerate qubits in a regime where coherence times can be long, even for natural silicon. This addressability is not only important for donor-dot quantum computing schemes like the one described by Pica et al 10 , but also for other quantum computing architectures relying on the use of more than two donor spin states.…”

Section: Figmentioning

confidence: 99%

“…By varying this polarization, we demonstrate the selective addressability of the 7.03 GHz clock transitions. This will be important for hybrid donor-dot quantum computing schemes since the 5 GHz clock transition was recently predicted to form an avoided crossing with silicon based quantum dots 10 . This was discussed in the donor-dot surface code proposal by Pica et al 10 which also suggested addressing the clock transitions using microwave polarization.…”

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confidence: 99%

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Addressing spin transitions onBi209donors in silicon using circularly polarized microwaves

et al. 2016

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Over the past decade donor spin qubits in isotopically enriched 28 Si have been intensely studied due to their exceptionally long coherence times. More recently bismuth donor electron spins have become popular because Bi has a large nuclear spin which gives rise to clock transitions (first-order insensitive to magnetic field noise). At every clock transition there are two nearly degenerate transitions between four distinct states which can be used as a pair of qubits. Here it is experimentally demonstrated that these transitions are excited by microwaves of opposite helicity such that they can be selectively driven by varying microwave polarization. This work uses a combination of a superconducting coplanar waveguide (CPW) microresonator and a dielectric resonator to flexibly generate arbitrary elliptical polarizations while retaining the high sensitivity of the CPW.Donors spins in Si are among the most promising quantum bits owing to their long coherence times (T 2 ) which exceed seconds in isotopically enriched 28 Si 1-4 . Bismuth donor electrons are particularly attractive because they have clock transitions which are first order insensitive to magnetic field noise [5][6][7][8][9] . This means that even in natural Si, electron spins can have long coherence times 5 . In Bi doped Si clock transitions come in pairs of nearly degenerate transitions separated by ∼1 MHz. These are predicted to be excited by microwaves of opposite circular polarization 7,10 . In this work we combine a coplanar waveguide microresonator (CPW) with a dielectric resonator to generate microwaves with tunable polarization. By varying this polarization, we demonstrate the selective addressability of the 7.03 GHz clock transitions. This will be important for hybrid donor-dot quantum computing schemes since the 5 GHz clock transition was recently predicted to form an avoided crossing with silicon based quantum dots 10 . This was discussed in the donor-dot surface code proposal by Pica et al 10 which also suggested addressing the clock transitions using microwave polarization.Bismuth donors in Si have a large hyperfine coupling which not only gives rise to a large zero field splitting, but also allows for rapid manipulation of both the electronic and nuclear spin states when operating in the intermediate field regime where the hyperfine coupling is comparable to the Zeeman splitting 8,[11][12][13] . In this regime we describe the states using the total spin, F , and its projection, m F 6 . The total spin is given by F = I ± S where I is the nuclear spin and S is the electron spin. At the 7.03 GHz clock transition the two nearly degenerate transitions are described in the |F, m F basis by |5, −1 ⇔ |4, −2 and |5, −2 ⇔ |4, −1 . In the high field limit the second transition is forbidden since it involves a nuclear spin flip, but due to strong mixing, both transitions are accessible near the clock transition. By convention we will still refer to the |5, −1 ⇔ |4, −2 transition as allowed and the |5, −2 ⇔ |4, −1 transition as forbidden. These transi...

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Surface code architecture for donors and dots in silicon with imprecise and nonuniform qubit couplings

Cited by 64 publications

References 50 publications

Donor hyperfine Stark shift and the role of central-cell corrections in tight-binding theory

Donor hyperfine Stark shift and the role of central-cell corrections in tight-binding theory

Logical Qubit in a Linear Array of Semiconductor Quantum Dots

Addressing spin transitions onBi209donors in silicon using circularly polarized microwaves

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