Multicore Quantum Computing

Jnane, Hamza; Undseth, Brennan; Cai, Zhenyu; Benjamin, Simon C; Koczor, Bálint

doi:10.48550/arxiv.2201.08861

Cited by 5 publications

(9 citation statements)

References 109 publications

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“…Such a network might involve quantum computers interlinked within a building, analogously to a conventional High Performance Computing facility, and relevant methods of linking processors have been experimentally realized. Alternatively, for suitably compact platforms, the network might correspond to linked quantum computing processors on a single chip, analogous to today's multicore central processing units; multicore quantum computing has recently been explored (49). In either case, it is realistic to assume that in a network of processor nodes, the internode operations are slower than the intranode ones.…”

Section: Quantum Computer Architecturesmentioning

confidence: 99%

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Grid-based methods for chemistry simulations on a quantum computer

et al. 2023

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First-quantized, grid-based methods for chemistry modeling are a natural and elegant fit for quantum computers. However, it is infeasible to use today’s quantum prototypes to explore the power of this approach because it requires a substantial number of near-perfect qubits. Here, we use exactly emulated quantum computers with up to 36 qubits to execute deep yet resource-frugal algorithms that model 2D and 3D atoms with single and paired particles. A range of tasks is explored, from ground state preparation and energy estimation to the dynamics of scattering and ionization; we evaluate various methods within the split-operator QFT (SO-QFT) Hamiltonian simulation paradigm, including protocols previously described in theoretical papers and our own techniques. While we identify certain restrictions and caveats, generally, the grid-based method is found to perform very well; our results are consistent with the view that first-quantized paradigms will be dominant from the early fault-tolerant quantum computing era onward.

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Section: Quantum Computer Architecturesmentioning

confidence: 99%

“…The "comms resources" would thus correspond to Bell pair distribution, purification, and buffering. Such processes can occur independently of the main computation and simultaneously with it and need not involve a large number of qubits; see, for example, the analysis in (49,50).…”

Section: Quantum Computer Architecturesmentioning

confidence: 99%

Grid-based methods for chemistry simulations on a quantum computer

et al. 2023

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“…In semiconductor spin qubits, each step of shuttling can be carried out by tipping the electrical potential of an occupied quantum dot to transfer the spin into an adjacent quantum dot adiabatically. Various modes such as 'bucket brigade' [50] and 'conveyor' [51] have been explored, and high fidelity shuttling on the timescale of nanoseconds is expected to be possible [12,[52][53][54][55] with the corresponding shuttling speed being tens of m s −1 . Hence, the shuttling step will not be the rate-limiting step in the pipeline.…”

Section: Pipelining Surface Codes Using Semiconductor Spin Qubits a I...mentioning

confidence: 99%

“…Only interacting qubits are brought together through qubit shuttling. As a result, qubit shuttling forms the basis for many of the most promising scalable architectures for platforms like semiconductor spin qubits [10][11][12] and trapped-ion qubits [13][14][15][16][17]. The related question of how to efficiently exploit the shuttling capabilities using suitable control sequences is also considered in Refs [18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Looped Pipelines Enabling Effective 3D Qubit Lattices in a Strictly 2D Device

Cai¹,

Siegel²,

Benjamin³

2022

Preprint

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Many quantum computing platforms are based on a fundamentally two-dimensional physical layout. However, there are advantages (for example in fault-tolerant systems) to having a 3D architecture. Here we explore a concept called looped pipelines which permits one to obtain many of the advantages of a 3D lattice while operating a strictly 2D device. The concept leverages qubit shuttling, a well-established feature in platforms like semiconductor spin qubits and trappedion qubits. The looped pipeline architecture has similar hardware requirements to other shuttling approaches, but can process a stack of qubit arrays instead of just one. Simple patterns of intra-and inter-loop interactions allow one to embody diverse schemes from NISQ-era error mitigation through to fault-tolerant codes. For the former, protocols involving multiple states can be implemented with a similar space-time resource as preparing one noisy copy. For the latter, one can realise a far broader variety of code structures; in particular, we consider a stack of 2D codes within which transversal CNOTs are available. We find that this can achieve a cost saving of up to a factor of ∼ 80 in the space-time overhead for magic state distillation (and a factor of ∼ 200 with modest additional hardware). Using numerical modelling and experimentally-motivated noise models we verify that the looped pipeline approach provides these benefits without significant reduction in the code's threshold.

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“…Recently, this approach was integrated in the blueprint of a sparse spin qubit array compatible with industrial fabrication without providing details on control and spin coherence of the shuttling process [22]. Alternatively, the shuttling can be used to distribute entangled pairs of electrons to distant arrays (cores), in order to provide coherent communication between them [31]. The charge of a single electron has already been transferred in Si/SiGe over a distance of nine tunnel-coupled QDs [32] using Landau-Zener charge transitions [29,[33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Blueprint of a scalable spin qubit shuttle device for coherent mid-range qubit transfer in disordered Si/SiGe/SiO$_2$

Langrock¹,

Krzywda²,

Focke³

et al. 2022

Preprint

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Silicon spin qubits stand out due to their very long coherence times, compatibility with industrial fabrication, and prospect to integrate classical control electronics. To achieve a truly scalable architecture, a coherent mid-range link between qubit registers has been suggested to solve the signal fan-out problem. Here we present a blueprint of such a ∼ 10 µm long link, called a spin qubit shuttle, which is based on connecting an array of gates into a small number of sets. The number of these gate sets and thus the number of required control signal is independent of the link distance to coherently shuttle the electron qubit. We discuss two different operation modes for the spin qubit shuttle: A qubit conveyor, i.e. a potential minimum that smoothly moves laterally, and a bucket brigade, in which the electron is transported through a series of tunnel-coupled quantum dots by adiabatic passage. We find the former approach more promising considering a realistic Si/SiGe device including potential disorder from the charged defects at the Si/SiO2 layer, as well as typical charge noise. Focusing on the qubit transfer fidelity of the conveyor shuttling mode, motional narrowing, the interplay between orbital and valley excitation and relaxation in presence of g-factors that depend on orbital and valley state of the electron, and effects from spin-hotspots are discussed in detail. We find that a transfer fidelity of 99.9 % is feasible in Si/SiGe at a speed of ∼10 m/s, if the average valley splitting and its inhomogeneity stay within realistic bounds. Operation at low global magnetic field ≈ 20 mT and material engineering towards high valley splitting is favourable to reach high transfer fidelities.

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Multicore Quantum Computing

Cited by 5 publications

References 109 publications

Grid-based methods for chemistry simulations on a quantum computer

Grid-based methods for chemistry simulations on a quantum computer

Looped Pipelines Enabling Effective 3D Qubit Lattices in a Strictly 2D Device

Blueprint of a scalable spin qubit shuttle device for coherent mid-range qubit transfer in disordered Si/SiGe/SiO$_2$

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