1
|
Chiesa A, Santini P, Garlatti E, Luis F, Carretta S. Molecular nanomagnets: a viable path toward quantum information processing? REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:034501. [PMID: 38314645 DOI: 10.1088/1361-6633/ad1f81] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 01/17/2024] [Indexed: 02/06/2024]
Abstract
Molecular nanomagnets (MNMs), molecules containing interacting spins, have been a playground for quantum mechanics. They are characterized by many accessible low-energy levels that can be exploited to store and process quantum information. This naturally opens the possibility of using them as qudits, thus enlarging the tools of quantum logic with respect to qubit-based architectures. These additional degrees of freedom recently prompted the proposal for encoding qubits with embedded quantum error correction (QEC) in single molecules. QEC is the holy grail of quantum computing and this qudit approach could circumvent the large overhead of physical qubits typical of standard multi-qubit codes. Another important strength of the molecular approach is the extremely high degree of control achieved in preparing complex supramolecular structures where individual qudits are linked preserving their individual properties and coherence. This is particularly relevant for building quantum simulators, controllable systems able to mimic the dynamics of other quantum objects. The use of MNMs for quantum information processing is a rapidly evolving field which still requires to be fully experimentally explored. The key issues to be settled are related to scaling up the number of qudits/qubits and their individual addressing. Several promising possibilities are being intensively explored, ranging from the use of single-molecule transistors or superconducting devices to optical readout techniques. Moreover, new tools from chemistry could be also at hand, like the chiral-induced spin selectivity. In this paper, we will review the present status of this interdisciplinary research field, discuss the open challenges and envisioned solution paths which could finally unleash the very large potential of molecular spins for quantum technologies.
Collapse
Affiliation(s)
- A Chiesa
- Dipartimento di Scienze Matematiche, Fisiche e Informatiche, Università di Parma, I-43124 Parma, Italy
- INFN-Sezione di Milano-Bicocca, Gruppo Collegato di Parma, 43124 Parma, Italy
- UdR Parma, INSTM, I-43124 Parma, Italy
| | - P Santini
- Dipartimento di Scienze Matematiche, Fisiche e Informatiche, Università di Parma, I-43124 Parma, Italy
- INFN-Sezione di Milano-Bicocca, Gruppo Collegato di Parma, 43124 Parma, Italy
- UdR Parma, INSTM, I-43124 Parma, Italy
| | - E Garlatti
- Dipartimento di Scienze Matematiche, Fisiche e Informatiche, Università di Parma, I-43124 Parma, Italy
- INFN-Sezione di Milano-Bicocca, Gruppo Collegato di Parma, 43124 Parma, Italy
- UdR Parma, INSTM, I-43124 Parma, Italy
| | - F Luis
- Instituto de Nanociencia y Materiales de Aragon (INMA), CSIC, Universidad de Zaragoza, Zaragoza, Spain
- Departamento de Fısica de la Materia Condensada, Universidad de Zaragoza, Zaragoza, Spain
| | - S Carretta
- Dipartimento di Scienze Matematiche, Fisiche e Informatiche, Università di Parma, I-43124 Parma, Italy
- INFN-Sezione di Milano-Bicocca, Gruppo Collegato di Parma, 43124 Parma, Italy
- UdR Parma, INSTM, I-43124 Parma, Italy
| |
Collapse
|
2
|
Román-Roche J, Luis F, Zueco D. Photon Condensation and Enhanced Magnetism in Cavity QED. PHYSICAL REVIEW LETTERS 2021; 127:167201. [PMID: 34723605 DOI: 10.1103/physrevlett.127.167201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 08/25/2021] [Accepted: 08/25/2021] [Indexed: 06/13/2023]
Abstract
A system of magnetic molecules coupled to microwave cavities (LC resonators) undergoes the equilibrium superradiant phase transition. The transition is experimentally observable. The effect of the coupling is first illustrated by the vacuum-induced ferromagnetic order in a quantum Ising model and then by the modification of the magnetic phase diagram of Fe_{8} dipolar crystals, exemplifying the cooperation between intrinsic and photon-induced spin-spin interactions. Finally, a transmission experiment is shown to resolve the transition, measuring the quantum electrodynamical control of magnetism.
Collapse
Affiliation(s)
- Juan Román-Roche
- Instituto de Nanociencia y Materiales de Aragón (INMA) and Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, Zaragoza 50009, Spain
| | - Fernando Luis
- Instituto de Nanociencia y Materiales de Aragón (INMA) and Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, Zaragoza 50009, Spain
| | - David Zueco
- Instituto de Nanociencia y Materiales de Aragón (INMA) and Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, Zaragoza 50009, Spain
| |
Collapse
|
3
|
Lenz S, König D, Hunger D, van Slageren J. Room-Temperature Quantum Memories Based on Molecular Electron Spin Ensembles. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2101673. [PMID: 34106491 DOI: 10.1002/adma.202101673] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 05/06/2021] [Indexed: 06/12/2023]
Abstract
Whilst quantum computing has recently taken great leaps ahead, the development of quantum memories has decidedly lagged behind. Quantum memories are essential devices in the quantum technology palette and are needed for intermediate storage of quantum bit states and as quantum repeaters in long-distance quantum communication. Current quantum memories operate at cryogenic, mostly sub-Kelvin temperatures and require extensive and costly peripheral hardware. It is demonstrated that ensembles of weakly coupled molecular spins show long coherence times and can be used to store microwave pulses of arbitrary phase. These studies exploit strong coupling of the spin ensemble to special 3D microwave resonators. Most importantly, these systems operate at room temperature.
Collapse
Affiliation(s)
- Samuel Lenz
- Institute of Physical Chemistry and Center for Integrated Quantum Science and Technology, University of Stuttgart, Pfaffenwaldring 55, D-70569, Stuttgart, Germany
| | - Dennis König
- Institute of Physical Chemistry and Center for Integrated Quantum Science and Technology, University of Stuttgart, Pfaffenwaldring 55, D-70569, Stuttgart, Germany
| | - David Hunger
- Institute of Physical Chemistry and Center for Integrated Quantum Science and Technology, University of Stuttgart, Pfaffenwaldring 55, D-70569, Stuttgart, Germany
| | - Joris van Slageren
- Institute of Physical Chemistry and Center for Integrated Quantum Science and Technology, University of Stuttgart, Pfaffenwaldring 55, D-70569, Stuttgart, Germany
| |
Collapse
|
4
|
Gimeno I, Kersten W, Pallarés MC, Hermosilla P, Martínez-Pérez MJ, Jenkins MD, Angerer A, Sánchez-Azqueta C, Zueco D, Majer J, Lostao A, Luis F. Enhanced Molecular Spin-Photon Coupling at Superconducting Nanoconstrictions. ACS NANO 2020; 14:8707-8715. [PMID: 32441922 DOI: 10.1021/acsnano.0c03167] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We combine top-down and bottom-up nanolithography to optimize the coupling of small molecular spin ensembles to 1.4 GHz on-chip superconducting resonators. Nanoscopic constrictions, fabricated with a focused ion beam at the central transmission line, locally concentrate the microwave magnetic field. Drops of free-radical molecules have been deposited from solution onto the circuits. For the smallest ones, the molecules were delivered at the relevant circuit areas by means of an atomic force microscope. The number of spins Neff effectively coupled to each device was accurately determined combining Scanning Electron and Atomic Force Microscopies. The collective spin-photon coupling constant has been determined for samples with Neff ranging between 2 × 106 and 1012 spins, and for temperatures down to 44 mK. The results show the well-known collective enhancement of the coupling proportional to the square root of Neff. The average coupling of individual spins is enhanced by more than 4 orders of magnitude (from 4 mHz up to above 180 Hz), when the transmission line width is reduced from 400 μm down to 42 nm, and reaches maximum values near 1 kHz for molecules located on the smallest nanoconstrictions.
Collapse
Affiliation(s)
- Ignacio Gimeno
- Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Wenzel Kersten
- Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, 1020 Vienna, Austria
| | - María C Pallarés
- Laboratorio de Microscopı́as Avanzadas, Instituto de Nanociencia de Aragón, Universidad de Zaragoza, 50018 Zaragoza, Spain
| | - Pablo Hermosilla
- Laboratorio de Microscopı́as Avanzadas, Instituto de Nanociencia de Aragón, Universidad de Zaragoza, 50018 Zaragoza, Spain
| | - María José Martínez-Pérez
- Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
- Fundación ARAID, Av. de Ranillas 1-D, 50018 Zaragoza, Spain
| | - Mark D Jenkins
- Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Andreas Angerer
- Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, 1020 Vienna, Austria
| | | | - David Zueco
- Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
- Fundación ARAID, Av. de Ranillas 1-D, 50018 Zaragoza, Spain
| | - Johannes Majer
- Shanghai Branch, CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, 1020 Vienna, Austria
| | - Anabel Lostao
- Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
- Laboratorio de Microscopı́as Avanzadas, Instituto de Nanociencia de Aragón, Universidad de Zaragoza, 50018 Zaragoza, Spain
- Fundación ARAID, Av. de Ranillas 1-D, 50018 Zaragoza, Spain
| | - Fernando Luis
- Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
| |
Collapse
|
5
|
Shim J, Kim SJ, Kim SK, Lee KJ. Enhanced Magnon-Photon Coupling at the Angular Momentum Compensation Point of Ferrimagnets. PHYSICAL REVIEW LETTERS 2020; 125:027205. [PMID: 32701310 DOI: 10.1103/physrevlett.125.027205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 06/18/2020] [Indexed: 06/11/2023]
Abstract
We theoretically show that the coupling between magnons in an antiferromagnetically coupled ferrimagnet and microwave photons in a cavity is largely enhanced at the angular momentum compensation point (T_{A}) when T_{A} is distinct from the magnetization compensation point. The origin of the enhanced magnon-photon coupling at T_{A} is identified as the antiferromagnetic spin dynamics combined with a finite magnetization. Moreover, we show that strong magnon-photon coupling can be achieved at high excitation frequency in a ferrimagnet, which is challenging to achieve for a ferromagnet due to low magnon frequency and for an antiferromagnet due to weak magnon-photon coupling. Our results will invigorate research on magnon-photon coupling by proposing ferrimagnets as a versatile platform that offers advantages of both ferromagnets and antiferromagnets.
Collapse
Affiliation(s)
- Jaechul Shim
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Korea
- Semiconductor R&D Center, Samsung Electronics Co. Ltd., Hwaseong, Gyeonggi 18448, Korea
| | - Seok-Jong Kim
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
| | - Se Kwon Kim
- Department of Physics, KAIST, Daejeon 34141, Korea
- Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211, USA
| | - Kyung-Jin Lee
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
| |
Collapse
|
6
|
Lenz S, Hunger D, van Slageren J. Strong coupling between resonators and spin ensembles in the presence of exchange couplings. Chem Commun (Camb) 2020; 56:12837-12840. [DOI: 10.1039/d0cc04841k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Exchange–dependent strong coupling between DPPH radical spins and 3D microwave cavity coupling up to room temperature.
Collapse
Affiliation(s)
- Samuel Lenz
- Institute of Physical Chemistry and Center for Integrated Quantum Science and Technology IQST
- University of Stuttgart
- Stuttgart 70569
- Germany
| | - David Hunger
- Institute of Physical Chemistry and Center for Integrated Quantum Science and Technology IQST
- University of Stuttgart
- Stuttgart 70569
- Germany
| | - Joris van Slageren
- Institute of Physical Chemistry and Center for Integrated Quantum Science and Technology IQST
- University of Stuttgart
- Stuttgart 70569
- Germany
| |
Collapse
|
7
|
Abstract
Spins in solids or in molecules possess discrete energy levels, and the associated quantum states can be tuned and coherently manipulated by means of external electromagnetic fields. Spins therefore provide one of the simplest platforms to encode a quantum bit (qubit), the elementary unit of future quantum computers. Performing any useful computation demands much more than realizing a robust qubit-one also needs a large number of qubits and a reliable manner with which to integrate them into a complex circuitry that can store and process information and implement quantum algorithms. This 'scalability' is arguably one of the challenges for which a chemistry-based bottom-up approach is best-suited. Molecules, being much more versatile than atoms, and yet microscopic, are the quantum objects with the highest capacity to form non-trivial ordered states at the nanoscale and to be replicated in large numbers using chemical tools.
Collapse
|
8
|
Johansen Ø, Brataas A. Nonlocal Coupling between Antiferromagnets and Ferromagnets in Cavities. PHYSICAL REVIEW LETTERS 2018; 121:087204. [PMID: 30192613 DOI: 10.1103/physrevlett.121.087204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Indexed: 06/08/2023]
Abstract
Microwaves couple to magnetic moments in both ferromagnets and antiferromagnets. Although the magnons in ferromagnets and antiferromagnets radically differ, they can become entangled via strong coupling to the same microwave mode in a cavity. The equilibrium configuration of the magnetic moments crucially governs the coupling between the different magnons, because the antiferromagnetic and ferromagnetic magnons have opposite spins when their dispersion relations cross. We derive analytical expressions for the coupling strengths and find that the coupling between antiferromagnets and ferromagnets is comparable to the coupling between two ferromagnets. Our findings reveal a robust link between cavity spintronics with ferromagnets and antiferromagnets.
Collapse
Affiliation(s)
- Øyvind Johansen
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Arne Brataas
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| |
Collapse
|