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We study the realization of a Toffoli gate with superconducting qubits in a circuit-QED setup using quantum-control methods. Starting with optimized piecewise-constant control fields acting on all qubits and typical strengths of XY-type…

Quantum Physics · Physics 2012-02-14 Vladimir M. Stojanovic , A. Fedorov , A. Wallraff , C. Bruder

The quantum computation of molecular response properties on near-term quantum hardware is a topic of significant interest. While computing time-domain response properties is in principle straightforward due to the natural ability of quantum…

The fidelity of certain gates on noisy quantum computers may be improved when they are implemented using more than two levels of the involved transmons. The main impediments to achieving this potential are the dynamic gate phase errors that…

Quantum Physics · Physics 2024-07-30 Yutaro Iiyama , Wonho Jang , Naoki Kanazawa , Ryu Sawada , Tamiya Onodera , Koji Terashi

The effective use of current Noisy Intermediate-Scale Quantum (NISQ) devices is often limited by the noise which is caused by interaction with the environment and affects the fidelity of quantum gates. In transmon qubit systems, the quantum…

Quantum Physics · Physics 2022-09-05 Elisha Siddiqui Matekole , Yao-Lung L. Fang , Meifeng Lin

Compared with the idea of universal quantum computation, a direct synthesis of a multiqubit logic gate can greatly improve the efficiency of quantum information processing tasks. Here we propose an efficient scheme to implement a…

Quantum Physics · Physics 2020-12-02 H. D. Yin , X. X. Li , G. C. Wang , X. Q. Shao

We use machine learning techniques to design a 50 ns three-qubit flux-tunable controlled-controlled-phase gate with fidelity of >99.99% for nearest-neighbor coupled transmons in circuit quantum electrodynamics architectures. We explain our…

We propose an efficiently measurable lower bound on quantum process fidelity of N-qubit controlled-Z gates. This bound is determined by average output state fidelities for N partially conjugate product bases. A distinct advantage of our…

A single-shot Toffoli, or controlled-controlled-NOT, gate is desirable for classical and quantum information processing. The Toffoli gate alone is universal for reversible computing and, accompanied by the Hadamard gate, forms a universal…

Quantum Physics · Physics 2015-05-21 Ehsan Zahedinejad , Joydip Ghosh , Barry C. Sanders

Three-qubit gates can be constructed using combinations of single-qubit and two-qubit gates, making their independent realization unnecessary. However, direct implementation of three-qubit gates reduces the depth of quantum circuits,…

We report the implementation of universal two- and three-qubit entangling gates on neutral atom qubits encoded in long-lived hyperfine ground states. The gates are mediated by excitation to strongly interacting Rydberg states, and are…

Quantum dot-based spin qubit realization is one of the most promising quantum computing systems owing to its integrability with classical computation hardware and its versatility in realizing qubits and quantum gates. In this work, we…

Quantum Physics · Physics 2024-11-14 Yash Tiwari , Aditya Dev , Vishvendra Singh Poonia

We present theoretical schemes for performing high-fidelity one- and two-qubit pulsed gates for a superconducting flux qubit. The "IBM qubit" consists of three Josephson junctions, three loops, and a superconducting transmission line.…

Quantum Physics · Physics 2008-03-19 Frederico Brito , David P. DiVincenzo , Roger H. Koch , Matthias Steffen

One of the key challenges in current Noisy Intermediate-Scale Quantum (NISQ) computers is to control a quantum system with high-fidelity quantum gates. There are many reasons a quantum gate can go wrong -- for superconducting transmon…

Building a quantum computer is a daunting challenge since it requires good control but also good isolation from the environment to minimize decoherence. It is therefore important to realize quantum gates efficiently, using as few operations…

Quantum Physics · Physics 2019-10-28 T. Bækkegaard , L. B. Kristensen , N. J. S. Loft , C. K. Andersen , D. Petrosyan , N. T. Zinner

Quantum computation is conventionally performed using quantum operations acting on two-level quantum bits, or qubits. Qubits in modern quantum computers suffer from inevitable detrimental interactions with the environment that cause errors…

Quantum Physics · Physics 2021-09-03 Alexey Galda , Michael Cubeddu , Naoki Kanazawa , Prineha Narang , Nathan Earnest-Noble

We introduce a simple, widely applicable formalism for designing "error-divisible" two qubit gates: a quantum gate set where fractional rotations have proportionally reduced error compared to the full entangling gate. In current noisy…

Quantum Physics · Physics 2021-10-25 David Rodriguez Perez , Paul Varosy , Ziqian Li , Tanay Roy , Eliot Kapit , David Schuster

Isolated spins in semiconductors provide a promising platform to explore quantum mechanical coherence and develop engineered quantum systems. Silicon has attracted great interest as a host material for developing spin qubits because of its…

Mesoscale and Nanoscale Physics · Physics 2015-10-29 Dohun Kim , D. R. Ward , C. B. Simmons , D. E. Savage , M. G. Lagally , Mark Friesen , S. N. Coppersmith , Mark A. Eriksson

We propose a scheme of fast three-qubit Toffoli quantum gate for ultracold neutral-atom qubits. The scheme is based on the Stark-tuned three-body F\"{o}rster resonances, which we have observed in our recent experiment [D.B.Tretyakov et al.,…

Native multi-qubit parity gates have various potential quantum computing applications, such as entanglement creation, logical state encoding and parity measurement in quantum error correction. Here, using simultaneous cross-resonance drives…

Quantum Physics · Physics 2023-10-06 Toshinari Itoko , Moein Malekakhlagh , Naoki Kanazawa , Maika Takita

Numerous scientific developments in this NISQ-era (Noisy Intermediate Scale Quantum) have raised the importance for quantum algorithms relative to their conventional counterparts due to its asymptotic advantage. For resource estimates in…

Quantum Physics · Physics 2023-09-13 Amit Saha , Anupam Chattopadhyay , Amlan Chakrabarti