Chip-to-chip entanglement of transmon qubits using engineered measurement fields

Dickel, Christian; Wesdorp, Jaap J.; Langford, Nathan K.; Peiter, Sarwan; Sagastizabal, Ramiro; Bruno, Alessandro; Criger, Ben; Motzoi, Felix; DiCarlo, L.

doi:10.1103/physrevb.97.064508

Cited by 41 publications

(29 citation statements)

References 71 publications

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“…The shared Bell pairs do not even need to have a high fidelity, as software-based entanglement distillation [39,40] can be used to convert a large number of low-fidelity Bell pairs into fewer high-fidelity Bell pairs. Recent experiments have made progress towards generating entanglement between different superconducting chips [41][42][43].…”

Section: Distributed Quantum Computingmentioning

confidence: 99%

A Game of Surface Codes: Large-Scale Quantum Computing with Lattice Surgery

Litinski

2019

Quantum

210

296

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Given a quantum gate circuit, how does one execute it in a fault-tolerant architecture with as little overhead as possible?In this paper, we discuss strategies for surface-code quantum computing on small, intermediate and large scales. They are strategies for space-time tradeoffs, going from slow computations using few qubits to fast computations using many qubits. Our schemes are based on surface-code patches, which not only feature a low space cost compared to other surface-code schemes, but are also conceptually simple -simple enough that they can be described as a tile-based game with a small set of rules. Therefore, no knowledge of quantum error correction is necessary to understand the schemes in this paper, but only the concepts of qubits and measurements.The field of quantum computing is fuelled by the promise of fast solutions to classically intractable problems, such as simulating large quantum systems or factoring large numbers. Already ∼100 qubits can be used to solve useful problems that are out of reach for classical computers [1,2]. Despite the exponential speedup, the actual time required to solve these problems is orders of magnitude above the coherence times of any physical qubit. In order to store and manipulate quantum information on large time scales, it is necessary to actively correct errors by combining many physical qubits into logical qubits using a quantum errorcorrecting code [3][4][5]. Of particular interest are codes that are compatible with the locality constraints of realistic devices such as superconducting qubits, which are limited to operations that are local in two dimensions. The most prominent such code is the surface code [6,7].Working with logical qubits introduces additional overhead to the computation. Not only is the space cost drastically increased as physical qubits are replaced by logical qubits, but also the time cost increases due to the restricted set of accessible logical operations. Surface codes, in particular, are limited to a set of 2Dlocal operations, which means that arbitrary gates in a quantum circuit may require several time steps instead of just one. To keep the cost of surface-code quantum computing low, it is important to find schemes that translate quantum circuits into surface-code layouts with a low space-time overhead. This is also necessary to benchmark how well quantum algorithms per-form in a surface-code architecture.There exist several encoding schemes for surface codes, among others, defect-based [7], twist-based [8] and patch-based [9] encodings. In this work, we focus on the latter. Surface-code patches have a low space overhead compared to other schemes, and offer lowoverhead Clifford gates [10,11]. In addition, they are conceptually less difficult to understand, as they do not directly involve braiding of topological defects. Designing computational schemes with surface-code patches only requires the concepts of qubits and measurements. To this end, we describe the operations of surface-code patches as a tile-based game. This is helpful t...

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Section: Distributed Quantum Computingmentioning

confidence: 99%

A Game of Surface Codes: Large-Scale Quantum Computing with Lattice Surgery

Litinski

2019

Quantum

210

296

View full text Add to dashboard Cite

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“…Remote entanglement between superconducting qubits has been realized probabilistically [12][13][14]. Conversely, realizing deterministic photonic communication requires releasing a single photon from one qubit and catching it with the remote qubit.…”

Section: Introductionmentioning

confidence: 99%

“…This limit is exceeded by dynamically tailoring the emission and absorption profiles [17][18][19][20]. These capabilities are presently being used to perform photonic communication between superconducting qubits connected by a transmission line within a cryostat [21][22][23][24]. In these experiments, the use of a circulator enables the finite-length transmission line to be modeled as a long line with a continuum density of states, at the cost of added transmission loss.…”

Section: Introductionmentioning

confidence: 99%

Deterministic bidirectional communication and remote entanglement generation between superconducting qubits

Leung

Chakram

et al. 2019

npj Quantum Inf

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We propose and experimentally demonstrate a simple and efficient scheme for photonic communication between two remote superconducting modules. Each module consists of a random access quantum information processor with eightqubit multimode memory and a single flux tunable transmon. The two processor chips are connected through a one-meter long coaxial cable that is coupled to a dedicated "communication" resonator on each chip. The two communication resonators hybridize with a mode of the cable to form a dark "communication mode" that is highly immune to decay in the coaxial cable. We modulate the transmon frequency via a parametric drive to generate sideband interactions between the transmon and the communication mode. We demonstrate bidirectional single-photon transfer with a success probability exceeding 60%, and generate an entangled Bell pair with a fidelity of 79.3 ± 0.3%. * These authors contributed equally to this work.

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“…contributed equally to this work.philipp.kurpiers@phys.ethz.ch, mpechal@stanford.edu, andreas.wallraff@phys.ethz.ch example, a simple encoding as a superposition of the vacuum state |0 and the single photon Fock state |1 is not suitable to detect errors due to photon loss because the error does not cause a transition out of the encoding subspace {|0 , |1 }. For this reason, encodings using other degrees of freedom such as polarization [28, 29], angular momentum [30, 31], frequency [32], time-bin [33-36] or path [37,38] are more common at optical frequencies.Heralding schemes have been used with superconducting circuits in the context of measurement based generation of remote entanglement [9,39] and also using two-photon interference [40]. The more recent deterministic state transfer and remote entanglement protocols based on the exchange of shaped photon wave packets [13][14][15]41] have to the best of our knowledge not yet been augmented using heralding protocols.…”

mentioning

confidence: 99%

“…Heralding schemes have been used with superconducting circuits in the context of measurement based generation of remote entanglement [9,39] and also using two-photon interference [40]. The more recent deterministic state transfer and remote entanglement protocols based on the exchange of shaped photon wave packets [13][14][15]41] have to the best of our knowledge not yet been augmented using heralding protocols.…”

mentioning

confidence: 99%

Quantum Communication with Time-Bin Encoded Microwave Photons

et al. 2019

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Heralding techniques are useful in quantum communication to circumvent losses without resorting to error correction schemes or quantum repeaters. Such techniques are realized, for example, by monitoring for photon loss at the receiving end of the quantum link while not disturbing the transmitted quantum state. We describe and experimentally benchmark a scheme that incorporates error detection in a quantum channel connecting two transmon qubits using traveling microwave photons. This is achieved by encoding the quantum information as a time-bin superposition of a single photon, which simultaneously realizes high communication rates and high fidelities. The presented scheme is straightforward to implement in circuit QED and is fully microwave-controlled, making it an interesting candidate for future modular quantum computing architectures.Engineering of large-scale quantum systems will likely require coherent exchange of quantum states between distant units. The concept of quantum networks has been studied theoretically [1][2][3][4] and substantial experimental efforts have been devoted to distribute entanglement over increasingly larger distances [5][6][7][8][9][10][11][12][13][14][15]. In practice, quantum links inevitably experience losses, which vary significantly between different architectures and may range from 2×10 −4 dB/m in optical fibers [16] to 5×10 −3 dB/m in superconducting coaxial cables and waveguides at cryogenic temperatures [17]. However, no matter which architecture is used, the losses over a sufficiently long link will eventually destroy the coherence of the transmitted quantum state, unless some measures are taken to mitigate these losses. Possible ways to protect the transmitted quantum information rely, for example, on using quantum repeaters [18,19], error correcting schemes [20][21][22] or heralding protocols [23][24][25][26], which allow one to retransmit the information in case photon loss is detected.Heralding protocols are particularly appealing for near-term scaling of quantum systems since they are implementable without a significant resource overhead and can provide deterministic remote entanglement at predetermined times [27]. In essence, these protocols rely on encoding the transmitted quantum information in a suitably chosen subspace S such that any error, which may be encountered during transmission, causes the system to leave this subspace. On the receiving end, a measurement which determines whether the system is in S but does not distinguish between individual states within S, can be used to detect if an error occurred. Crucially, when the transfer is successful, this protocol does not disturb the transmitted quantum information. As a counter * P.K. and M.P. contributed equally to this work.philipp.kurpiers@phys.ethz.ch, mpechal@stanford.edu, andreas.wallraff@phys.ethz.ch example, a simple encoding as a superposition of the vacuum state |0 and the single photon Fock state |1 is not suitable to detect errors due to photon loss because the error does not cause a transition out ...

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Chip-to-chip entanglement of transmon qubits using engineered measurement fields

Cited by 41 publications

References 71 publications

A Game of Surface Codes: Large-Scale Quantum Computing with Lattice Surgery

A Game of Surface Codes: Large-Scale Quantum Computing with Lattice Surgery

Deterministic bidirectional communication and remote entanglement generation between superconducting qubits

Quantum Communication with Time-Bin Encoded Microwave Photons

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