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:1910.11326 · Physical Review A

Mesoscopic spin systems as quantum entanglers

Maryam Sadat Mirkamali, David G. Cory

Published Mar 16, 2020• 4 citations
arXivHTMLPDF

Abstract

We quantify the resources required for entangling two uncoupled spin qubits through an intermediate mesoscopic spin system (MSS) by indirect joint measurement. Indirect joint measurement benefits from coherent magnification of the target qubits' state in the collective magnetization of the MSS, such that a low-resolution collective measurement on the MSS suffices to prepare postselected entanglement on the target qubits. A MSS consisting of two noninteracting halves, each coupled to one of the target qubits, is identified as a geometry that allows implementing the magnification process with experimentally available control tools. It is proved that the requirements on the amplified state of the target qubits and the MSS perfectly map to the specifications of micro-macro entanglement between each target qubit and its nearby half of the MSS. In the light of this equivalence, the effects of experimental imperfections are explored; in particular, bipartite entanglement between the target qubits is shown to be robust to imperfect preparation of the MSS. Our study provides an approach for using an intermediate spin system for connecting separated qubits. It also opens another path in exploring entanglement between microscopic and mesoscopic spin systems.

DOI
10.1103/physreva.101.032320

Related papers

Resources Needed for Entangling Two Qubits through an Intermediate Mesoscopic System

Maryam Sadat Mirkamali

One of the main challenges in designing large scale quantum processors is connecting separated qubits. In this thesis, we explore new opportunities that mesoscopic many-body systems provide for creating quantum correlation between isolated quantum systems. In particular, we study entangling two non-interacting qubits through an intermediate mesoscopic system consisting of identical two-level systems. Two uncoupled qubits can be entangled either by projectively measuring a joint property of them or by creating an indirect interaction between them. The focus of this thesis is on procedures that are based on joint measurement on the qubits. \nWe propose a new method for entangling two non-interacting qubits by measuring their parity indirectly through an intermediate mesoscopic system. Indirect joint measurement scheme benefits from coherent magnification of the target qubits’ state in the collective state of the mesoscopic system; such that a low-resolution measurement on the mesoscopic system suffices to prepare post-selected entanglement on the target qubits. The protocol is designed to require only global control and course-grained collective measurement of the mesoscopic system along with local interactions between the target qubits and mesoscopic system. A generalization of the method measures the hamming weight of the qubits’ state and probabilistically produces an entangled state by post-selecting on hamming weight one. Our technique provides a new design element that can be integrated into quantum processor architectures and quantum measurement devices. \nWe quantify the resources required for implementing the indirect joint measurement technique when the intermediate mesoscopic system consists of spin-1/2 particles with internal dipolar coupling. A mesoscopic spin system consisting of two non-interacting halves, each coupled to one of the target qubits is proved to provide a helpful geometry that allows implementing the coherent magnification process with experimentally available control tools. We show that the requirements on the amplified state of the target qubits and the mesoscopic spin system perfectly maps to the specifications of micro-macro entanglement between each target qubit and its nearby half of the mesoscopic spin system. In the light of this equivalence, the effects of experimental imperfections are explored; in particular, bipartite entanglement between the target qubits is shown to be robust to imperfect preparation of the mesoscopic spin system. Our analysis provides a new approach for using an intermediate spin system for connecting separated qubits. It also opens a new path in exploring entanglement between microscopic and mesoscopic spin systems.

•Sep 23, 2019•2 citations

Entanglement of two noninteracting qubits via a mesoscopic system

Maryam Sadat Mirkamali, David G. Cory, Joseph Emerson

We propose a method for entangling two noninteracting qubits by measuring their parity indirectly through an intermediate mesoscopic system. The protocol is designed to require only global control and course-grained collective measurement of the mesoscopic system along with local interactions between the target qubits and mesoscopic system. A generalization of the method measures the hamming weight of the qubits' state and probabilistically produces an entangled state by post-selecting on hamming weight one. Our technique provides a design element that can be integrated into quantum processor architectures and quantum measurement devices.

arXiv:1802.05320•Physical Review A•Oct 18, 2018•5 citations

Mesoscopic entanglement of noninteracting qubits using collective spontaneous emission

D. Kielpinski

We describe an experimentally straightforward method for preparing an entangled W state of at least 100 qubits. Our repeat-until-success protocol relies on detection of single photons from collective spontaneous emission in free space. Our method allows entanglement preparation in a wide range of qubit implementations that lack entangling qubit–qubit interactions. We give detailed numerical examples for entanglement of neutral atoms in optical lattices and of nitrogen-vacancy centres in diamond. The simplicity of our method should enable preparation of mesoscopic entangled states in a number of physical systems in the near future.

arXiv:quant-ph/0701066•New Journal of Physics•Nov 14, 2007•5 citations

Mesoscopic entanglement of noninteracting qubits using collective spontaneous emission

D. Kielpinski

We describe an experimentally straightforward method for preparing an entangled W state of up to 100 qubits. Our repeat-until-success protocol relies on detection of single photons from collective spontaneous emission in free space. Our method allows entanglement preparation in a wide range of qubit implementations that lack entangling qubit-qubit interactions. We give detailed numerical examples for entanglement of neutral atoms in optical lattices and of nitrogen-vacancy centres in diamond. The simplicity of our method should enable preparation of mesoscopic entangled states in a number of physical systems in the near future.

•Jan 12, 2007•2 citations

Partitioning dysprosium's electronic spin to reveal entanglement in nonclassical states

Tanish Satoor, Aurélien Fabre, Jean-Baptiste Bouhiron +3 more

Quantum spins of mesoscopic size are a well-studied playground for engineering nonclassical states. If the spin represents the collective state of an ensemble of qubits, its nonclassical behavior is linked to entanglement between the qubits. In this paper, we report on an experimental study of entanglement between two subsystems of dysprosium's electronic spin. Its ground state, of angular momentum $J=8$, can formally be viewed as a set of $2J$ qubits symmetric upon exchange. To access entanglement properties, we partition the spin by optically coupling it to an excited state ${J}^{\ensuremath{'}}=J\ensuremath{-}1$, which removes a pair of qubits in a state defined by the light polarization. Starting with the well-known W and squeezed states, we extract the concurrence of qubit pairs, which quantifies their nonclassical character. We also directly demonstrate entanglement between the 14- and 2-qubit subsystems via an increase in entropy upon partition. In a complementary set of experiments, we probe decoherence of a state prepared in the excited level ${J}^{\ensuremath{'}}=J+1$ and interpret spontaneous emission as a loss of a qubit pair in a random state. This allows us to contrast the robustness of nonclassical pairwise correlations of the W state with the fragility of the coherence involved in a Schr\"odinger cat state. Our findings open up the possibility to engineer novel types of entangled atomic ensembles, in which entanglement occurs within each atom's electronic spin as well as between different atoms. Qubit ensembles with large entanglement depth could then be realized with a few atoms only, facilitating the scaling up of quantum-enhanced sensors.

arXiv:2104.14389•Physical Review Research•Oct 1, 2021•12 citations

Preparation of Macroscopic Entangled Coherent States in Nitrogen-Vacancy Centers Ensembles Coupled to a Superconducting Flux Qubit*

Liang-Wei Wang, Zhang-Cai Long

Abstract We propose a potentially practical scheme for creating macroscopic entangled coherent state between two separate nitrogen-vacancy center spin ensembles placed near a superconducting flux qubit. Through the collective magnetic coupling and the in situ tunability of the flux qubit, the arbitrary entangled coherent states of spin ensembles can be achieved with high success possibilities under the influence from decoherence of the flux qubit and spin ensembles. The experimental feasibility and challenge are justified using currently available technology.

Communications in Theoretical Physics•Jun 1, 2017•2 citations
We quantify the resources required for entangling two uncoupled spin qubits through an intermediate mesoscopic spin system (MSS) by indirect joint measurement. Indirect joint measurement benefits from coherent magnification of the target qubits' state in the collective magnetization of the MSS, such that a low-resolution collective measurement on the MSS suffices to prepare postselected entanglement on the target qubits. A MSS consisting of two noninteracting halves, each coupled to one of the target qubits, is identified as a geometry that allows implementing the magnification process with experimentally available control tools. It is proved that the requirements on the amplified state of the target qubits and the MSS perfectly map to the specifications of micro-macro entanglement between each target qubit and its nearby half of the MSS. In the light of this equivalence, the effects of experimental imperfections are explored; in particular, bipartite entanglement between the target qubits is shown to be robust to imperfect preparation of the MSS. Our study provides an approach for using an intermediate spin system for connecting separated qubits. It also opens another path in exploring entanglement between microscopic and mesoscopic spin systems.
One of the main challenges in designing large scale quantum processors is connecting separated qubits. In this thesis, we explore new opportunities that mesoscopic many-body systems provide for creating quantum correlation between isolated quantum systems. In particular, we study entangling two non-interacting qubits through an intermediate mesoscopic system consisting of identical two-level systems. Two uncoupled qubits can be entangled either by projectively measuring a joint property of them or by creating an indirect interaction between them. The focus of this thesis is on procedures that are based on joint measurement on the qubits. \nWe propose a new method for entangling two non-interacting qubits by measuring their parity indirectly through an intermediate mesoscopic system. Indirect joint measurement scheme benefits from coherent magnification of the target qubits’ state in the collective state of the mesoscopic system; such that a low-resolution measurement on the mesoscopic system suffices to prepare post-selected entanglement on the target qubits. The protocol is designed to require only global control and course-grained collective measurement of the mesoscopic system along with local interactions between the target qubits and mesoscopic system. A generalization of the method measures the hamming weight of the qubits’ state and probabilistically produces an entangled state by post-selecting on hamming weight one. Our technique provides a new design element that can be integrated into quantum processor architectures and quantum measurement devices. \nWe quantify the resources required for implementing the indirect joint measurement technique when the intermediate mesoscopic system consists of spin-1/2 particles with internal dipolar coupling. A mesoscopic spin system consisting of two non-interacting halves, each coupled to one of the target qubits is proved to provide a helpful geometry that allows implementing the coherent magnification process with experimentally available control tools. We show that the requirements on the amplified state of the target qubits and the mesoscopic spin system perfectly maps to the specifications of micro-macro entanglement between each target qubit and its nearby half of the mesoscopic spin system. In the light of this equivalence, the effects of experimental imperfections are explored; in particular, bipartite entanglement between the target qubits is shown to be robust to imperfect preparation of the mesoscopic spin system. Our analysis provides a new approach for using an intermediate spin system for connecting separated qubits. It also opens a new path in exploring entanglement between microscopic and mesoscopic spin systems.
We propose a method for entangling two noninteracting qubits by measuring their parity indirectly through an intermediate mesoscopic system. The protocol is designed to require only global control and course-grained collective measurement of the mesoscopic system along with local interactions between the target qubits and mesoscopic system. A generalization of the method measures the hamming weight of the qubits' state and probabilistically produces an entangled state by post-selecting on hamming weight one. Our technique provides a design element that can be integrated into quantum processor architectures and quantum measurement devices.
We describe an experimentally straightforward method for preparing an entangled W state of at least 100 qubits. Our repeat-until-success protocol relies on detection of single photons from collective spontaneous emission in free space. Our method allows entanglement preparation in a wide range of qubit implementations that lack entangling qubit–qubit interactions. We give detailed numerical examples for entanglement of neutral atoms in optical lattices and of nitrogen-vacancy centres in diamond. The simplicity of our method should enable preparation of mesoscopic entangled states in a number of physical systems in the near future.
We describe an experimentally straightforward method for preparing an entangled W state of up to 100 qubits. Our repeat-until-success protocol relies on detection of single photons from collective spontaneous emission in free space. Our method allows entanglement preparation in a wide range of qubit implementations that lack entangling qubit-qubit interactions. We give detailed numerical examples for entanglement of neutral atoms in optical lattices and of nitrogen-vacancy centres in diamond. The simplicity of our method should enable preparation of mesoscopic entangled states in a number of physical systems in the near future.
Quantum spins of mesoscopic size are a well-studied playground for engineering nonclassical states. If the spin represents the collective state of an ensemble of qubits, its nonclassical behavior is linked to entanglement between the qubits. In this paper, we report on an experimental study of entanglement between two subsystems of dysprosium's electronic spin. Its ground state, of angular momentum J=8J=8J=8, can formally be viewed as a set of 2J2J2J qubits symmetric upon exchange. To access entanglement properties, we partition the spin by optically coupling it to an excited state ${J}^{\ensuremath{'}}=J\ensuremath{-}1$, which removes a pair of qubits in a state defined by the light polarization. Starting with the well-known W and squeezed states, we extract the concurrence of qubit pairs, which quantifies their nonclassical character. We also directly demonstrate entanglement between the 14- and 2-qubit subsystems via an increase in entropy upon partition. In a complementary set of experiments, we probe decoherence of a state prepared in the excited level ${J}^{\ensuremath{'}}=J+1$ and interpret spontaneous emission as a loss of a qubit pair in a random state. This allows us to contrast the robustness of nonclassical pairwise correlations of the W state with the fragility of the coherence involved in a Schr\"odinger cat state. Our findings open up the possibility to engineer novel types of entangled atomic ensembles, in which entanglement occurs within each atom's electronic spin as well as between different atoms. Qubit ensembles with large entanglement depth could then be realized with a few atoms only, facilitating the scaling up of quantum-enhanced sensors.
Abstract We propose a potentially practical scheme for creating macroscopic entangled coherent state between two separate nitrogen-vacancy center spin ensembles placed near a superconducting flux qubit. Through the collective magnetic coupling and the in situ tunability of the flux qubit, the arbitrary entangled coherent states of spin ensembles can be achieved with high success possibilities under the influence from decoherence of the flux qubit and spin ensembles. The experimental feasibility and challenge are justified using currently available technology.