Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2509.04825 · Physical Review Research

Control protocol for dynamic synthesis of qubit and qudit gates using photonic pulses and magnetic fields

Andrés F. Urquijo-Rodríguez, Edgar A. Gómez, Herbert Vinck-Posada

Published Sep 16, 2025• 0 citations
arXivHTMLPDF

Abstract

We propose a theoretical control protocol designed for the dynamic synthesis of single-qubit and four-level qudit quantum gates using external parameters, such as photonic Gaussian pulses and magnetic fields, in a microcavity-quantum well system. Our approach takes advantage of tunable coherent light-matter interactions that can be modulated by the magnetic field between the exciton and negative trion coupled to the lowest photonic mode. We demonstrate that it is possible to achieve precise manipulation of populations of encoded quantum states through the unitary evolution of the system. In particular, we illustrate our optimization method for generating a single-qubit gate with a mean fidelity of 99.99 as well as the realization of an iswap gate in the four-level qudit case with a fidelity of 99.6.

DOI
10.1103/b8q1-hn3f

Related papers

Dynamics of qudit gates and effects of spectator modes on optimal control pulses

A. Barış Özgüler, Joshua Job

Qudit gates for high-dimensional quantum computing can be synthesized with high precision using numerical quantum optimal control techniques. Large circuits are broken down into modules and the tailored pulses for each module can be used as primitives for a qudit compiler. Application of the pulses of each module in the presence of extra modes may decrease their effectiveness due to crosstalk. In this paper, we address this problem by simulating qudit dynamics for circuit quantum electrodynamics systems. As a test case, we take pulses for single-qudit swap gates optimized in isolation and then apply them in the presence of spectator modes each of which are in Fock states. We provide an experimentally relevant scaling formula that can be used as a bound on the fidelity decay. Our results show that frequency shift from spectator mode populations has to be $\ensuremath{\lesssim}0.1%$ of the qudit's nonlinearity in order for high-fidelity single-qudit gates to be useful in the presence of occupied spectator modes.

arXiv:2207.14006•Physical Review A•May 1, 2024•4 citations

Optimal Control of Molecular Spin Qudits

Alberto Castro, Adrián García Carrizo, Sebastián Roca-Jerat +2 more

We demonstrate, numerically, the possibility of manipulating the spin states of molecular nanomagnets with shaped microwave pulses designed with quantum optimal control theory techniques. The state-to-state or full gate transformations can be performed in this way in shorter times than using simple monochromatic resonant pulses. This enhancement in the operation rates can therefore mitigate the effect of decoherence. The optimization protocols and their potential for practical implementations are illustrated by simulations performed for a simple molecular cluster hosting a single ${\mathrm{Gd}}^{3+}$ ion. Its eight accessible levels (corresponding to a total spin $S=7/2$) allow encoding an eight-level qudit or a system of three coupled qubits. All necessary gates required for universal operation can be obtained with optimal pulses using the intrinsic couplings present in this system. The application of optimal control techniques can facilitate the implementation of quantum technologies based on molecular spin qudits.

Physical Review Applied•Jun 14, 2022•46 citations

Optimal control of molecular spin qudits

Castro, Alberto, Adrián García Carrizo, David Zueco +1 more

We demonstrate, numerically, the possibility of manipulating the spin states of molecular nanomagnets with shaped microwave pulses designed with quantum optimal control theory techniques. The state-to-state or full gate transformations can be performed in this way in shorter times than using simple monochromatic resonant pulses. This enhancement in the operation rates can therefore mitigate the effect of decoherence. The optimization protocols and their potential for practical implementations are illustrated by simulations performed for a simple molecular cluster hosting a single Gd$^{3+}$ ion. Its eight accessible levels (corresponding to a total spin $S=7/2$) allow encoding an $8$-level qudit or a system of three coupled qubits. All necessary gates required for universal operation can be obtained with optimal pulses using the intrinsic couplings present in this system. The application of optimal control techniques can facilitate the implementation of quantum technologies based on molecular spin qudits.

arXiv:2111.15313•Nov 30, 2021•0 citations

Components for quantum computing based on optical transitions in single quantum dots

Matthew A. Pooley

The optically active nature of direct bandgap semiconductors makes them well suited for applications in quantum optics. Semiconductor quantum dots (QDs) are particularly promising, due to their discrete atom-like energy levels. In this thesis, transitions between these energy levels are used to investigate the effects of electric and magnetic fields on the energy structure of single QDs, with a view to developing applications in the field of quantum computing. In the work presented here a novel method of creating entangled photon pair emitters is presented, in which an electric field is used to tune the energy structure of single QDs to allow the fidelity of the emitted entangled state to be increased. In addition, a technique for the creation of energy-tunable entangled photon pairs is proposed and shown to be feasible with current technology. Furthermore, the potential of QDs to act as an interface between photonic and spin qubits is explored. Application of a time varying electric field is used to dynamically tune the QD energy levels, allowing the evolution of excitons confined within single QDs to be manipulated. Using this system a controlled phase rotation of the exciton spin state is implemented. Finally, indistinguishable single photons, emitted by the radiative decay of the exciton state, are used to generate the input state for an integrated photonic two-qubit quantum logic gate. This is the first demonstration of a two-qubit gate using on-demand single photons. It is also the first demonstration of such a gate with all components realised using semiconductor materials.

•Mar 1, 2013•0 citations

Numerical Gate Synthesis for Quantum Heuristics on Bosonic Quantum Processors

A. Barış Özgüler

There is a recent surge of interest and insights regarding the interplay of quantum optimal control and variational quantum algorithms. We study the framework in the context of qudits which are, for instance, definable as controllable electromagnetic modes of a superconducting cavity system coupled to a transmon. By employing recent quantum optimal control approaches described in (Peterson and Garcia, 2021), we showcase universal control of single-qudit operations up to 8 states, and two-qutrit operations, mapped respectively on a single mode and two modes of the resonator. We discuss the results of numerical pulse engineering on the closed system for parametrized gates useful to implement quantum approximate optimization (QAOA) qudits algorithms. The results show that high fidelity (> 0.99) is achievable with sufficient computational effort on HPC for most cases under study, and extension to multiple modes and open, noisy systems are possible. The tailored pulses can be stored and used as calibrated primitives for a future compiler in cQED systems.

•Dec 13, 2021•1 citation

Numerical gate synthesis for quantum heuristics on bosonic quantum processors

A. Barış Özgüler, Davide Venturelli

There is a recent surge of interest and insights regarding the interplay of quantum optimal control and variational quantum algorithms. We study the framework in the context of qudits which are, for instance, definable as controllable electromagnetic modes of a superconducting cavity system coupled to a transmon. By employing recent quantum optimal control approaches described in (Petersson and Garcia, 2021), we showcase control of single-qudit operations up to eight states, and two-qutrit operations, mapped respectively onto a single mode and two modes of the resonator. We discuss the results of numerical pulse engineering on the closed system for parametrized gates useful to implement Quantum Approximate Optimization Algorithm (QAOA) for qudits. The results show that high fidelity ( > 0.99) is achievable with sufficient computational effort for most cases under study, and extensions to multiple modes and open, noisy systems are possible. The tailored pulses can be stored and used as calibrated primitives for a future compiler in circuit quantum electrodynamics (cQED) systems.

arXiv:2201.07787•Frontiers in Physics•Oct 20, 2022•16 citations
We propose a theoretical control protocol designed for the dynamic synthesis of single-qubit and four-level qudit quantum gates using external parameters, such as photonic Gaussian pulses and magnetic fields, in a microcavity-quantum well system. Our approach takes advantage of tunable coherent light-matter interactions that can be modulated by the magnetic field between the exciton and negative trion coupled to the lowest photonic mode. We demonstrate that it is possible to achieve precise manipulation of populations of encoded quantum states through the unitary evolution of the system. In particular, we illustrate our optimization method for generating a single-qubit gate with a mean fidelity of 99.99 as well as the realization of an iswap gate in the four-level qudit case with a fidelity of 99.6.
Qudit gates for high-dimensional quantum computing can be synthesized with high precision using numerical quantum optimal control techniques. Large circuits are broken down into modules and the tailored pulses for each module can be used as primitives for a qudit compiler. Application of the pulses of each module in the presence of extra modes may decrease their effectiveness due to crosstalk. In this paper, we address this problem by simulating qudit dynamics for circuit quantum electrodynamics systems. As a test case, we take pulses for single-qudit swap gates optimized in isolation and then apply them in the presence of spectator modes each of which are in Fock states. We provide an experimentally relevant scaling formula that can be used as a bound on the fidelity decay. Our results show that frequency shift from spectator mode populations has to be $\ensuremath{\lesssim}0.1%$ of the qudit's nonlinearity in order for high-fidelity single-qudit gates to be useful in the presence of occupied spectator modes.
We demonstrate, numerically, the possibility of manipulating the spin states of molecular nanomagnets with shaped microwave pulses designed with quantum optimal control theory techniques. The state-to-state or full gate transformations can be performed in this way in shorter times than using simple monochromatic resonant pulses. This enhancement in the operation rates can therefore mitigate the effect of decoherence. The optimization protocols and their potential for practical implementations are illustrated by simulations performed for a simple molecular cluster hosting a single Gd3+{\mathrm{Gd}}^{3+}Gd3+ ion. Its eight accessible levels (corresponding to a total spin S=7/2S=7/2S=7/2) allow encoding an eight-level qudit or a system of three coupled qubits. All necessary gates required for universal operation can be obtained with optimal pulses using the intrinsic couplings present in this system. The application of optimal control techniques can facilitate the implementation of quantum technologies based on molecular spin qudits.
We demonstrate, numerically, the possibility of manipulating the spin states of molecular nanomagnets with shaped microwave pulses designed with quantum optimal control theory techniques. The state-to-state or full gate transformations can be performed in this way in shorter times than using simple monochromatic resonant pulses. This enhancement in the operation rates can therefore mitigate the effect of decoherence. The optimization protocols and their potential for practical implementations are illustrated by simulations performed for a simple molecular cluster hosting a single Gd3+^{3+}3+ ion. Its eight accessible levels (corresponding to a total spin S=7/2S=7/2S=7/2) allow encoding an 888-level qudit or a system of three coupled qubits. All necessary gates required for universal operation can be obtained with optimal pulses using the intrinsic couplings present in this system. The application of optimal control techniques can facilitate the implementation of quantum technologies based on molecular spin qudits.
The optically active nature of direct bandgap semiconductors makes them well suited for applications in quantum optics. Semiconductor quantum dots (QDs) are particularly promising, due to their discrete atom-like energy levels. In this thesis, transitions between these energy levels are used to investigate the effects of electric and magnetic fields on the energy structure of single QDs, with a view to developing applications in the field of quantum computing. In the work presented here a novel method of creating entangled photon pair emitters is presented, in which an electric field is used to tune the energy structure of single QDs to allow the fidelity of the emitted entangled state to be increased. In addition, a technique for the creation of energy-tunable entangled photon pairs is proposed and shown to be feasible with current technology. Furthermore, the potential of QDs to act as an interface between photonic and spin qubits is explored. Application of a time varying electric field is used to dynamically tune the QD energy levels, allowing the evolution of excitons confined within single QDs to be manipulated. Using this system a controlled phase rotation of the exciton spin state is implemented. Finally, indistinguishable single photons, emitted by the radiative decay of the exciton state, are used to generate the input state for an integrated photonic two-qubit quantum logic gate. This is the first demonstration of a two-qubit gate using on-demand single photons. It is also the first demonstration of such a gate with all components realised using semiconductor materials.
There is a recent surge of interest and insights regarding the interplay of quantum optimal control and variational quantum algorithms. We study the framework in the context of qudits which are, for instance, definable as controllable electromagnetic modes of a superconducting cavity system coupled to a transmon. By employing recent quantum optimal control approaches described in (Peterson and Garcia, 2021), we showcase universal control of single-qudit operations up to 8 states, and two-qutrit operations, mapped respectively on a single mode and two modes of the resonator. We discuss the results of numerical pulse engineering on the closed system for parametrized gates useful to implement quantum approximate optimization (QAOA) qudits algorithms. The results show that high fidelity (> 0.99) is achievable with sufficient computational effort on HPC for most cases under study, and extension to multiple modes and open, noisy systems are possible. The tailored pulses can be stored and used as calibrated primitives for a future compiler in cQED systems.
There is a recent surge of interest and insights regarding the interplay of quantum optimal control and variational quantum algorithms. We study the framework in the context of qudits which are, for instance, definable as controllable electromagnetic modes of a superconducting cavity system coupled to a transmon. By employing recent quantum optimal control approaches described in (Petersson and Garcia, 2021), we showcase control of single-qudit operations up to eight states, and two-qutrit operations, mapped respectively onto a single mode and two modes of the resonator. We discuss the results of numerical pulse engineering on the closed system for parametrized gates useful to implement Quantum Approximate Optimization Algorithm (QAOA) for qudits. The results show that high fidelity ( > 0.99) is achievable with sufficient computational effort for most cases under study, and extensions to multiple modes and open, noisy systems are possible. The tailored pulses can be stored and used as calibrated primitives for a future compiler in circuit quantum electrodynamics (cQED) systems.