Modular Bosonic Subsystem Codes

Pantaleoni, Giacomo; Baragiola, Ben Q.; Menicucci, Nicolas C.

doi:10.1103/physrevlett.125.040501

Cited by 47 publications

(59 citation statements)

References 42 publications

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“…Our use of CV resources affords us an important alternative over existing approaches, wherein a qubit that failed to be produced must be erased from the lattice. Instead, we replace the no-show qubit with a squeezed vacuum state: it can still encode logical information (albeit not as well as a GKP state [43]) but has the distinction of being Gaussian and thus easily producible 2 . This approach -one of the main innovations in this work -propels us beyond existing fault tolerance methods, such as those that rely on lattice renormalization to deal with defects [6,[45][46][47].…”

Section: Overview Of Architecturementioning

confidence: 99%

“…The different layouts for the magic state factories, the data and the ancilla blocks, and the boundary conditions of the data patches can be easily modified by an appropriate selection of the homodyne measurement quadratures. Note that as long as the fraction of swap-outs is below a critical value (which depends on the squeezing ∆), the general structure of our computing scheme carries through in the presence of swap-outs: both the GKP states in the lattice and p-squeezed states encode |+ and act appropriately under the physical operations we discussed [43]. However, the swapped-out nodes add correlated noise to their neighborhood, an effect we deal with in the error-correction procedure, which we address in the following section.…”

Section: Magic State Injection and Distillationmentioning

confidence: 99%

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Blueprint for a Scalable Photonic Fault-Tolerant Quantum Computer

Bourassa

Alexander

Vasmer

et al. 2021

Quantum

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Photonics is the platform of choice to build a modular, easy-to-network quantum computer operating at room temperature. However, no concrete architecture has been presented so far that exploits both the advantages of qubits encoded into states of light and the modern tools for their generation. Here we propose such a design for a scalable fault-tolerant photonic quantum computer informed by the latest developments in theory and technology. Central to our architecture is the generation and manipulation of three-dimensional resource states comprising both bosonic qubits and squeezed vacuum states. The proposal exploits state-of-the-art procedures for the non-deterministic generation of bosonic qubits combined with the strengths of continuous-variable quantum computation, namely the implementation of Clifford gates using easy-to-generate squeezed states. Moreover, the architecture is based on two-dimensional integrated photonic chips used to produce a qubit cluster state in one temporal and two spatial dimensions. By reducing the experimental challenges as compared to existing architectures and by enabling room-temperature quantum computation, our design opens the door to scalable fabrication and operation, which may allow photonics to leap-frog other platforms on the path to a quantum computer with millions of qubits.

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Section: Overview Of Architecturementioning

confidence: 99%

Section: Magic State Injection and Distillationmentioning

confidence: 99%

Blueprint for a Scalable Photonic Fault-Tolerant Quantum Computer

Bourassa

Alexander

Vasmer

et al. 2021

Quantum

Self Cite

234

202

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show abstract

“…An alternative framework for reducing a bosonic state to a two-dimensional GKP qubit was recently proposed by Pantaleoni et al [17]. The idea is to decompose an arbitrary bosonic state | into a qubit part and a continuous part, i.e.,…”

Section: Modular Bosonic Subsystem Fidelitymentioning

confidence: 99%

“…Further details on this technique can be found in the Appendix and in Ref. [17]. Using this method we can again analyze the fidelity of ÛT |+ L with the target state in the qubit subspace, thus providing a complementary figure of merit.…”

Section: Modular Bosonic Subsystem Fidelitymentioning

confidence: 99%

Unsuitability of cubic phase gates for non-Clifford operations on Gottesman-Kitaev-Preskill states

et al. 2021

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With the Gottesman-Kitaev-Preskill (GKP) encoding, Clifford gates and error correction can be carried out using simple Gaussian operations. Still, non-Clifford gates, required for universality, require non-Gaussian elements. In their original proposal, GKP suggested a particularly simple method of using a single application of the cubic phase gate to perform the logical non-Clifford T gate. Here we show that this cubic phase gate approach performs extraordinarily poorly, even for arbitrarily large amounts of squeezing in the GKP state. Thus, contrary to common belief, the cubic phase gate is not suitable for achieving universal fault-tolerant quantum computation with GKP states.

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“…The problem of finding optimal ways to decompose an arbitrary gate into a product of gates from a given universal set is precisely the focus of this manuscript. The study of this problem also finds application when continuous degrees of freedom are used to encode error-correctable qubits, since the logical operations of the logical qubits need to be ultimately executed as continuous-variable gates [24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Exact and approximate continuous-variable gate decompositions

Kalajdzievski

Quesada

2021

Quantum

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We gather and examine in detail gate decomposition techniques for continuous-variable quantum computers and also introduce some new techniques which expand on these methods. Both exact and approximate decomposition methods are studied and gate counts are compared for some common operations. While each having distinct advantages, we find that exact decompositions have lower gate counts whereas approximate techniques can cover decompositions for all continuous-variable operations but require significant circuit depth for a modest precision.

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Modular Bosonic Subsystem Codes

Cited by 47 publications

References 42 publications

Blueprint for a Scalable Photonic Fault-Tolerant Quantum Computer

Blueprint for a Scalable Photonic Fault-Tolerant Quantum Computer

Unsuitability of cubic phase gates for non-Clifford operations on Gottesman-Kitaev-Preskill states

Exact and approximate continuous-variable gate decompositions

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