Article
Chemistry, Multidisciplinary
Stefan Henkel, Melania Prado Merini, Enrique Mendez-Vega, Wolfram Sander
Summary: For many thermal reactions, the effects of catalysis or solvents can be explained by transition state models, but reactions controlled by quantum tunneling lack this simple concept. Through Lewis acid catalysis, complexes with H2O and CF3I significantly increase the tunneling rates of a rearrangement reaction.
Article
Optics
Sahel Ashhab, Fumiki Yoshihara, Tomoko Fuse, Naoki Yamamoto, Adrian Lupascu, Kouichi Semba
Summary: This study examines the implementation of two-qubit gates in the presence of additional quantum states in the accessible energy range. The results show that the coupling between higher energy levels can increase the gate speed, while weak anharmonicity constrains the system's control speed. By modifying the pulse optimization algorithm, the impact of higher levels can be minimized. Furthermore, the optimal-control gate speeds are compared with those obtained using other protocols.
Article
Quantum Science & Technology
MengKe Feng, Lin Htoo Zaw, Teck Seng Koh
Summary: This study focuses on the implementation of high fidelity two-qubit gates in semiconductor quantum dot qubits and examines the effects of noise on the qubit parameters. Multiple two-qubit sweet spots (2QSS) were identified in the parameter space of capacitively coupled exchange-only (EO) spin qubits, providing valuable information on noise threshold for fault-tolerance. The comparison of gate fidelities and times at different parameter positions presents a potential route to achieving high fidelity quantum computation.
NPJ QUANTUM INFORMATION
(2021)
Article
Chemistry, Multidisciplinary
Dennis Schaefter, Jonathan Wischnat, Lorenzo Tesi, J. Alejandro De Sousa, Edmund Little, Jake McGuire, Marta Mas-Torrent, Concepcio Rovira, Jaume Veciana, Floriana Tuna, Nuria Crivillers, Joris van Slageren
Summary: General-purpose quantum computation and quantum simulation require precise and robust interqubit interactions in multi-qubit architectures, along with local addressability. Molecular systems, such as chlorinated triphenylmethyl organic radicals, show promise for large-scale quantum architectures due to their high degree of positionability and tailorability of interqubit interactions. This study demonstrates extraordinarily long coherence times up to 148 μs in the investigated molecular materials at temperatures below 100 K, and also showcases two-qubit and individual qubit addressability in the biradical system. These findings highlight the potential of molecular materials for the development of quantum architectures.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Dennis Schaefter, Jonathan Wischnat, Lorenzo Tesi, J. Alejandro De Sousa, Edmund Little, Jake McGuire, Marta Mas-Torrent, Concepcio Rovira, Jaume Veciana, Floriana Tuna, Nuria Crivillers, Joris van Slageren
Summary: In this article, the spin dynamics of chlorinated triphenylmethyl organic radicals were investigated, revealing long ensemble coherence times and the achievement of two-qubit and individual qubit addressability in the biradical system. These results highlight the potential of molecular materials in the development of quantum architectures.
ADVANCED MATERIALS
(2023)
Article
Physics, Multidisciplinary
Yotam Shapira, Sapir Cohen, Nitzan Akerman, Ady Stern, Roee Ozeri
Summary: In this study, we enhance the fidelity and robustness of entangling gates in quantum computers by introducing spin-dependent squeezing.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Ye-Qi Zhang, Xiao-Ting Ding, Jiao Sun, Tian-Hu Wang
Summary: We numerically study the quantum steering between two separated qubits trapped in a one-dimensional plasmonic waveguide. Our calculations show that steerability may exhibit a sudden disappearance and reappearance phenomenon, with time windows of no steerability but finite entanglement. The effects of plasmon wavenumber and the distance between the qubits on steerability are also examined. Furthermore, we demonstrate that quantum steerability can be tuned by adjusting the laser driving fields.
Article
Physics, Multidisciplinary
Yosep Kim, Alexis Morvan, Long B. Nguyen, Ravi K. Naik, Christian Junger, Larry Chen, John Mark Kreikebaum, David Santiago, Irfan Siddiqi
Summary: The development of noisy intermediate-scale quantum devices has brought about a wider range of executable high-fidelity single- and two-qubit gates. In this study, a high-fidelity iToffoli gate based on two-qubit interactions is demonstrated using fixed-frequency superconducting qubits. The gate implementation process achieves a fidelity of up to 98.26(2)%. Numerical simulations also show that the gate scheme used can produce more efficient three-qubit gates than the traditional Toffoli and iToffoli gates. This work not only introduces a high-fidelity iToffoli gate to current superconducting quantum processors, but also paves the way for developing multi-qubit gates based on two-qubit interactions.
Article
Quantum Science & Technology
Andrea Smirne, Simone Cialdi, Daniele Cipriani, Claudio Carmeli, Alessandro Toigo, Bassano Vacchini
Summary: This study describes and implements an experimental procedure for assessing the incompatibility of two qubit measurements. The experiment involves a state discrimination task and provides an upper bound for the amount of incompatibility. By tuning the preparation of the experiment, the upper bound can coincide with the true value of the incompatibility. The study demonstrates the practical feasibility of detecting quantum incompatibility using an optical setup.
QUANTUM SCIENCE AND TECHNOLOGY
(2022)
Article
Optics
Huiping Zhan, Huatang Tan
Summary: This paper investigates a scheme for achieving long-time sustainable Bell states of two distant qubits mediated by a one-dimensional waveguide. The scheme utilizes time-continuous photon counting or homodyne detection. Different Bell states can be obtained in the long-time regime, and the physical reasons behind them are analyzed. The scheme is advantageous for generating stable Bell states compared to previous studies.
Article
Physics, Multidisciplinary
Qi-Pei Liu, Cheng-Xian Zhang, Zheng-Yuan Xue
Summary: This paper proposes a method of utilizing simple quadrature pulses to correct errors of high frequency oscillatory terms induced by strong driving in order to improve the immunity of qubits to charge noise and achieve fast, high-fidelity single-qubit gate operation.
ACTA PHYSICA SINICA
(2023)
Article
Multidisciplinary Sciences
W. I. L. Lawrie, M. Rimbach-Russ, F. van Riggelen, N. W. Hendrickx, S. L. de Snoo, A. Sammak, G. Scappucci, J. Helsen, M. Veldhorst
Summary: As quantum processors scale up, the accurate characterization of errors due to crosstalks between qubits is important. This study presents a novel benchmarking protocol to analyze single-gate fidelities in a 2x2 hole spin qubit array in germanium. The results show high gate fidelities and robustness to crosstalk errors, providing crucial information for scaling up quantum information technology.
NATURE COMMUNICATIONS
(2023)
Article
Optics
Qi-Ping Su, Yu Zhang, Chui-Ping Yang
Summary: This study proposes a one-step implementation of a multi-target qubit controlled-NOT gate, where a superconducting qubit controls multiple cat-state qubits simultaneously. The gate operation is simple, quick, and independent of the number of target qubits.
Article
Quantum Science & Technology
Oscar Perdomo, Vicente Leyton-Ortega, Alejandro Perdomo-Ortiz
Summary: The study explores the set of two-qubit pure states with real amplitudes and their geometrical representation on a three-dimensional sphere. Maximally entangled states form two perpendicular disjoint circles, while unentangled states are π/4 units away from maximally entangled states. States connected by local gates are equidistant to the pair of circles.
QUANTUM INFORMATION PROCESSING
(2021)
Article
Chemistry, Physical
Gerd Kothe, Michail Lukaschek, Tomoaki Yago, Gerhard Link, Konstantin L. Ivanov, Tien-Sung Lin
Summary: Quantum entanglement has been achieved in various physical systems, including quantum dots, trapped atomic ions, and superconductors. In this study, specific molecular solids are proposed as promising alternative platforms for quantum entanglement. A model system involving triplet pentacene in a host single crystal at level anticrossing (LAC) conditions is presented, with experiments demonstrating the generation of 14-qubit entangled nuclear spin states. These results lay the foundation for large-scale quantum information processing with multiqubit entanglement states.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Letter
Physics, Multidisciplinary
David P. DiVincenzo, Christopher A. Fuchs
Article
Physics, Applied
Pascal Cerfontaine, Rene Otten, Hendrik Bluhm
PHYSICAL REVIEW APPLIED
(2020)
Article
Physics, Multidisciplinary
P. Bethke, R. P. G. McNeil, J. Ritzmann, T. Botzem, A. Ludwig, A. D. Wieck, H. Bluhm
PHYSICAL REVIEW LETTERS
(2020)
Article
Physics, Multidisciplinary
Daniel Zeuch, Fabian Hassler, Jesse J. Slim, David P. DiVincenzo
Article
Physics, Multidisciplinary
Martin Rymarz, Stefano Bosco, Alessandro Ciani, David P. DiVincenzo
Summary: The proposed circuit design consists of two Josephson junctions coupled by a nonreciprocal element, the gyrator, which is protected against common noise channels in superconducting circuits. By simulating the equivalent system of a single electron in a crystal under the influence of a strong magnetic field, the low-energy dynamics of the circuit are determined. The circuit can be used for passive quantum error correction and possible protocols for logical gates, state preparation, and readout are described.
Article
Quantum Science & Technology
Cica Gustiani, David P. DiVincenzo
Summary: In the standard Oracle model, the blind oracular quantum computation (BOQC) scheme separates the Oracle as a distinct node in a quantum network, enabling collaboration between the main client and the Oracle to run oracular quantum algorithms on a server without the server learning anything about the clients' computation. The enhanced BOQC scheme, known as BOQCo, can be run on a solid-state quantum network with minimal physical qubits while maintaining the same level of security as BOQC.
QUANTUM SCIENCE AND TECHNOLOGY
(2021)
Article
Physics, Multidisciplinary
Joel C. Pommerening, David P. DiVincenzo
Summary: In this article, we solve the coupled recurrence relations for eigenenergies and -vectors in nondegenerate Rayleigh-Schrodinger perturbation theory, while imposing the constraint of normalizing the approximate eigenvector to 1 in every order. The series can be expressed using diagrams introduced by Bloch in 1958, which were originally used for the degenerate and unnormalized case. Normalization increases the number of terms and introduces a nontrivial dependence on the diagrams' topology to the coefficients.
ANNALES HENRI POINCARE
(2022)
Article
Physics, Multidisciplinary
Pascal Cerfontaine, Tobias Hangleiter, Hendrik Bluhm
Summary: The paper introduces a method based on the filter function formalism to perturbatively compute quantum processes in the presence of correlated classical noise. By deriving a composition rule and utilizing a joint filter function, the quantum process of the whole sequence can be efficiently computed, allowing for the study of noise correlations' effects on gate sequences.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Applied
Isabel Nha Minh Le, Julian D. Teske, Tobias Hangleiter, Pascal Cerfontaine, Hendrik Bluhm
Summary: This article introduces a filter function formalism that can calculate gate fidelities in the presence of autocorrelated noise and combines it with optimal control algorithms to optimize control pulses for quantum gates. By comparison, the gradient-based method is found to be approximately 2 orders of magnitude faster than the gradient-free method for optimizing pulses.
PHYSICAL REVIEW APPLIED
(2022)
Article
Multidisciplinary Sciences
Christoph Berke, Evangelos Varvelis, Simon Trebst, Alexander Altland, David P. DiVincenzo
Summary: In this study, the stability of quantum processors developed by IBM, Delft, and Google consortia is investigated using the techniques of many-body localization theory. The results show that some of these platforms are dangerously close to an uncontrollable chaotic phase, highlighting the need for a balance between intentional disorder and nonlinear resonator coupling to avoid chaotic instabilities.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Applied
Julian David Teske, Pascal Cerfontaine, Hendrik Bluhm
Summary: QOPT is a software framework for simulating qubit dynamics and robust quantum optimal control, taking into account common experimental situations such as noise characteristics and experimental constraints. It enables the calculation of noise influence, consideration of control electronics limitations, and efficient optimization of control pulses.
PHYSICAL REVIEW APPLIED
(2022)
Article
Quantum Science & Technology
R-P Riwar, D. P. DiVincenzo
Summary: Quantum circuit theory is a powerful tool for predicting the dynamics of superconducting circuits. This study proposes a general method to construct a low-energy Hamiltonian based on the circuit geometry and the solution of external magnetic fields, revealing the rich dynamics resulting from the interplay between geometry and field distribution.
NPJ QUANTUM INFORMATION
(2022)
Article
Quantum Science & Technology
Inga Seidler, Tom Struck, Ran Xue, Niels Focke, Stefan Trellenkamp, Hendrik Bluhm, Lars R. Schreiber
Summary: Proof-of-principle demonstrates successful shuttling of single electrons in Si/SiGe quantum channel using propagating wave-potential. This approach requires only four sinusoidal control signals and achieves high fidelity shuttling, solving the signal-fanout problem.
NPJ QUANTUM INFORMATION
(2022)
Article
Optics
Cica Gustiani, David P. DiVincenzo
Summary: In this study, blind client-server quantum computation was practiced with the execution of a mystery quantum computation controlled by a client with limited quantum power on a powerful server. Tests were developed using different versions of the Grover algorithm to demonstrate the feasibility of the concept and the potential for implementing these protocols in experiments.
Article
Physics, Multidisciplinary
Tobias Hangleiter, Pascal Cerfontaine, Hendrik Bluhm
Summary: Correlated, non-Markovian noise in solid-state systems complicates the theoretical description of quantum information technologies. The filter-function formalism has been successful in characterizing the decay of coherence under such environments, enabling a detailed study of noise effects on algorithms and periodically driven systems. The method is suitable for numerical applications and is presented with the open-source Python software package filter_functions.
PHYSICAL REVIEW RESEARCH
(2021)
