Demonstrating a Continuous Set of Two-qubit Gates for Near-term Quantum Algorithms

Foxen, Brooks; Neill, Charles; Dunsworth, A.; Roushan, P.; Chiaro, B.; Megrant, A.; Kelly, J.; Chen, Zijun; Satzinger, Kevin J.; Barends, R.; Arute, Frank; Arya, Kunal; Babbush, Ryan; Bacon, Dave; Bardin, Joseph C.; Boixo, Sergio; Buell, David A.; Burkett, Brian; Chen, Yu; Collins, Roberto; Farhi, Edward; Fowler, Austin G.; Gidney, Craig; Giustina, Marissa; Graff, Rob; Harrigan, Matthew P.; Huang, Trent; Isakov, Sergei V.; Jeffrey, E.; Zhang, Jiang; Kafri, Dvir; Kechedzhi, Kostyantyn; Klimov, Paul V.; Korotkov, Alexander N.; Kostritsa, Fedor; Landhuis, David; Lucero, Erik; McClean, Jarrod R.; McEwen, Matt; Mi, Xiao; Mohseni, Masoud; Mutus, J.; Naaman, Ofer; Neeley, M.; Niu, Murphy Yuezhen; Petukhov, A.; Quintana, Chris; Rubin, Nicholas C.; Sank, D.; Smelyanskiy, Vadim; Vainsencher, A.; White, Theodore C.; Yao, Z. Jamie; Yeh, P.; Zalcman, Adam; Neven, Hartmut; Martinis, John M.

doi:10.1103/physrevlett.125.120504

Cited by 211 publications

(153 citation statements)

References 30 publications

(26 reference statements)

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“…[2][3][4][5][6][7][8][9] ), but state-of-the-art quantum platforms typically have physical error rates near 10 −3 (refs. [10][11][12][13][14] ). Quantum error correction [15][16][17] promises to bridge this divide by distributing quantum logical information across many physical qubits in such a way that errors can be detected and corrected.…”

Section: Exponential Suppression Of Bit or Phase Errors With Cyclic Error Correctionmentioning

confidence: 99%

See 1 more Smart Citation

Exponential suppression of bit or phase errors with cyclic error correction

Chen¹,

Satzinger²,

Atalaya³

et al. 2021

Nature

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229

125

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Realizing the potential of quantum computing requires sufficiently low logical error rates1. Many applications call for error rates as low as 10−15 (refs. 2–9), but state-of-the-art quantum platforms typically have physical error rates near 10−3 (refs. 10–14). Quantum error correction15–17 promises to bridge this divide by distributing quantum logical information across many physical qubits in such a way that errors can be detected and corrected. Errors on the encoded logical qubit state can be exponentially suppressed as the number of physical qubits grows, provided that the physical error rates are below a certain threshold and stable over the course of a computation. Here we implement one-dimensional repetition codes embedded in a two-dimensional grid of superconducting qubits that demonstrate exponential suppression of bit-flip or phase-flip errors, reducing logical error per round more than 100-fold when increasing the number of qubits from 5 to 21. Crucially, this error suppression is stable over 50 rounds of error correction. We also introduce a method for analysing error correlations with high precision, allowing us to characterize error locality while performing quantum error correction. Finally, we perform error detection with a small logical qubit using the 2D surface code on the same device18,19 and show that the results from both one- and two-dimensional codes agree with numerical simulations that use a simple depolarizing error model. These experimental demonstrations provide a foundation for building a scalable fault-tolerant quantum computer with superconducting qubits.

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Section: Exponential Suppression Of Bit or Phase Errors With Cyclic Error Correctionmentioning

confidence: 99%

“…Second, we implement a 26-ns controlled-Z (CZ) gate using a direct swap between the joint states 1, 1 and 0, 2 of the two qubits (refs. 14,36 ). As in ref.…”

Section: Exponential Suppression Of Bit or Phase Errors With Cyclic Error Correctionmentioning

confidence: 99%

Exponential suppression of bit or phase errors with cyclic error correction

Chen¹,

Satzinger²,

Atalaya³

et al. 2021

Nature

Self Cite

229

125

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“…With this structure, it is possible to realize coupling strengths ranging from completely off to tens of MHz. One can engineer a wide range of two-qubit gates through proper design of the three current bias waveforms for this circuit [ 67 ]. For instance, if the qubits are tuned into resonance and the coupling is enabled, a single excitation will oscillate back and forth between the qubits (that is, oscillation will occur between the probability amplitudes of the |01〉 and |10〉 states), and by properly setting the gate duration it is possible to engineer a gate where α 01 and α 10 are swapped.…”

Section: Coherent Control Of Quantum Processors Using Microwave Techniquesmentioning

confidence: 99%

Microwaves in Quantum Computing

2021

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Quantum information processing systems rely on a broad range of microwave technologies and have spurred development of microwave devices and methods in new operating regimes. Here we review the use of microwave signals and systems in quantum computing, with specific reference to three leading quantum computing platforms: trapped atomic ion qubits, spin qubits in semiconductors, and superconducting qubits. We highlight some key results and progress in quantum computing achieved through the use of microwave systems, and discuss how quantum computing applications have pushed the frontiers of microwave technology in some areas. We also describe open microwave engineering challenges for the construction of large-scale, fault-tolerant quantum computers.

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“…The single-qubit unitary operations are performed locally through external control fields and have been im- plemented with very high fidelity in various physical setups. The two-qubit entangling gate, however, can only be realized through interaction between the two qubits [17] and have been realized in quantum dots [56,60], dopant-based systems [38], optical lattices [14,46], ion traps [4,5,32,37,55], super conducting devices [8,30], Rydberg atoms [68] and diamond nitrogen-vacancy centers [39]. The demand for direct interaction makes the realization of twoqubit gates very challenging for distant qubits.…”

Section: Introductionmentioning

confidence: 99%

Parallel entangling gate operations and two-way quantum communication in spin chains

Yousefjani

Bayat

2021

Quantum

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The power of a quantum circuit is determined through the number of two-qubit entangling gates that can be performed within the coherence time of the system. In the absence of parallel quantum gate operations, this would make the quantum simulators limited to shallow circuits. Here, we propose a protocol to parallelize the implementation of two-qubit entangling gates between multiple users which are spatially separated, and use a commonly shared spin chain data-bus. Our protocol works through inducing effective interaction between each pair of qubits without disturbing the others, therefore, it increases the rate of gate operations without creating crosstalk. This is achieved by tuning the Hamiltonian parameters appropriately, described in the form of two different strategies. The tuning of the parameters makes different bilocalized eigenstates responsible for the realization of the entangling gates between different pairs of distant qubits. Remarkably, the performance of our protocol is robust against increasing the length of the data-bus and the number of users. Moreover, we show that this protocol can tolerate various types of disorders and is applicable in the context of superconductor-based systems. The proposed protocol can serve for realizing two-way quantum communication.

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Demonstrating a Continuous Set of Two-qubit Gates for Near-term Quantum Algorithms

Cited by 211 publications

References 30 publications

Exponential suppression of bit or phase errors with cyclic error correction

Exponential suppression of bit or phase errors with cyclic error correction

Microwaves in Quantum Computing

Parallel entangling gate operations and two-way quantum communication in spin chains

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