Experimental Demonstrations of Native Implementation of Boolean Logic Hamiltonian in a Superconducting Quantum Annealer

Saida, Daisuke; Yamanashi, Yuki; Hidaka, Mutsuo; Hirayama, Fuminori; Imafuku, Kentaro; Nagasawa, Shuichi; Kawabata, Shiro

doi:10.1109/tqe.2021.3106776

Cited by 5 publications

(11 citation statements)

References 25 publications

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“…An alternative method that is particularly suitable for solving combinatorial optimization problems is using quantum circuits for quantum annealing (QA). The advantages of quantum computation using QA over conventional methods are still under investigation, but practical demonstrations will be available in the near future [3][4][5][6][7][8][9][10][11][12][13][14] . A superconducting ux qubit is used in QA [3][4][5] .…”

Section: Introductionmentioning

confidence: 99%

Scalable Interconnection Using a Superconducting Flux Qubit

Saida

Hidaka

Makise

2023

Preprint

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To improve the performance of quantum computers, implementation technology that guarantees the scalability of the number of qubits is essential, and increasing the degrees of freedom in routing by 2.5-dimensional implementation is important for realizing the scalability of circuits. Here, we achieve long-distance coupling using a superconducting flux qubit enabling routing on the order of millimeters. We report the design for a reliable connection qubit with a proof-of-concept demonstration of quantum annealing. We perform experiments and simulations on suppressing errors due to coupling. The coupling status is strictly controllable, enabling elimination of crosstalk from the unintentional circuit region. A low-temperature flip-chip bonding technology is introduced for the 2.5-dimensional interconnection. The superconducting flux qubit, formed across two different chips via bumps, is demonstrated for the first time to show a state transition similar to that in a conventional qubit. The connection qubit and flip-chip bonding pave the way for new interconnections between different types of qubits. The possibility of interactions between gate-type qubits is investigated in a simulation.

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Section: Introductionmentioning

confidence: 99%

Scalable Interconnection Using a Superconducting Flux Qubit

Saida

Hidaka

Makise

2023

Preprint

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“…One possible way to construct the problem Hamiltonian without including many-body interactions is to express it as the circuit satisfiability (SAT) problem 21 , 22 . The ground-state spin logic 23 allows us to obtain the Hamiltonian when the input and output relationships are expressed by Boolean logic gates (cf : NOR gate) 24 – 26 . In the superconducting quantum circuit embedded in this Hamiltonian, qubit states play a role of inputs and outputs.…”

Section: Introductionmentioning

confidence: 99%

“…In the superconducting quantum circuit embedded in this Hamiltonian, qubit states play a role of inputs and outputs. We have proposed QA with a native implementation of the problem Hamiltonian for a superconducting quantum circuit composed of flux qubits with all-to-all connectivity, where direct magnetic couplers are utilized instead of variable couplers 24 . The problem Hamiltonian, which has a set of ground states consistent with a given truth table, is implemented for the circuit with no redundant qubits.…”

Section: Introductionmentioning

confidence: 99%

“…The problem Hamiltonian, which has a set of ground states consistent with a given truth table, is implemented for the circuit with no redundant qubits. This direct implementation of the original Hamiltonian is essential for obtaining solutions with high accuracy because the original energy relationship in the Hamiltonian is preserved 24 . Using this unique method, we have demonstrated QA in the Hamiltonian of logic gates and a multiplier 24 , 26 .…”

Section: Introductionmentioning

confidence: 99%

“…This direct implementation of the original Hamiltonian is essential for obtaining solutions with high accuracy because the original energy relationship in the Hamiltonian is preserved 24 . Using this unique method, we have demonstrated QA in the Hamiltonian of logic gates and a multiplier 24 , 26 . This allows us to obtain both a highly accurate solution and expandability of scaling.…”

Section: Introductionmentioning

confidence: 99%

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Superconducting quantum circuit of NOR in quantum annealing

Saida

Hidaka

Miyake

et al. 2022

Sci Rep

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The applicability of quantum annealing to various problems can be improved by expressing the Hamiltonian using a circuit satisfiability problem. We investigate the detailed characteristics of the NOR/NAND functions of a superconducting quantum circuit, which are the basic building blocks to implementing various types of problem Hamiltonians. The circuit is composed of superconducting flux qubits with all-to-all connectivity, where direct magnetic couplers are utilized instead of the variable couplers in the conventional superconducting quantum circuit. This configuration provides efficient scalability because the problem Hamiltonian is implemented using fewer qubits. We present an experiment with a complete logic operation of NOR/NAND, in which the circuit produces results with a high probability of success for arbitrary combinations of inputs. The features of the quantum circuit agree qualitatively with the theory, especially the mechanism for an operation under external flux modulation. Moreover, by calibrating the bias conditions to compensate for the offset flux from the surrounding circuit, the quantum circuit quantitatively agrees with the theory. To achieve true quantum annealing, we discuss the effects of the reduction in electric noise in quantum annealing.

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Scalable interconnection using a superconducting flux qubit

Saida,

Makise,

Hidaka

2024

Sci Rep

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Superconducting quantum computers are rapidly reaching scales where bottlenecks to scaling arise from the practical aspects of the fabrication process. To improve quantum computer performance, implementation technology that guarantees the scalability of the number of qubits is essential. Increasing the degrees of freedom in routing by 2.5-dimensional implementation is important for realizing circuit scalability. We report an implementation technology to overcome the scaling bottlenecks using a reliable connection qubit with a demonstration of quantum annealing. The method comprises interconnection based on quantum annealing using a superconducting flux qubit, precise coupling status control, and flip-chip bonding. We perform experiments and simulations with a proof-of-concept demonstration of qubit coupling via interconnection using a flux qubit. The coupling status is strictly controllable by quantum annealing. A low-temperature flip-chip bonding technology is introduced for the 2.5-dimensional interconnection. The superconducting flux qubit, formed across two different chips via bumps, is demonstrated for the first time to show a state transition like that in a conventional qubit. The quantum annealing flux qubit and flip-chip bonding enable new interconnections between qubits. A perspective on the possibility of applying this technology to the connection between gate-type qubits is described.

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Experimental Demonstrations of Native Implementation of Boolean Logic Hamiltonian in a Superconducting Quantum Annealer

Abstract: The devices were fabricated in CRAVITY, AIST in Japan. This paper is partly based on results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO), Japan (project number JPNP16007).

Cited by 5 publications

References 25 publications

Scalable Interconnection Using a Superconducting Flux Qubit

Scalable Interconnection Using a Superconducting Flux Qubit

Superconducting quantum circuit of NOR in quantum annealing

Scalable interconnection using a superconducting flux qubit

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