While molecular spin qubits (MSQs) are a promising platform for quantum computing, read-out has been largely limited to electron paramagnetic resonance which is often slow and requires a global system drive. Moreover, because one prerequisite for the Elzerman and Pauli spin blockade readout mechanisms typical of semiconductor spin qubits is tunneling of electrons between sites, these read-out modalities are unavailable in MSQs. Here, we theoretically demonstrate electrical read-out of entangled MSQs via driven many-electron spin unpolarized currents. In particular, using a time-dependent density matrix renormalization group approach we simulate a maximally entangled MSQ pair between two electronic leads. Driving itinerant electrons between the two leads, we find that the conductance is greater when the MSQs are in the entangled singlet state as compared to the entangled triplet state. This contrast in conductance is enhanced when the electronic density of states at the Fermi energy is large and for narrow bandwidth. Our results are readily applicable to molecules supramolecularly functionalizing semiconductors with relatively flat bands such as single-wall carbon nanotubes under a magnetic field.While molecular spin qubits (MSQs) are a promising platform for quantum computing, read-out has been largely limited to electron paramagnetic resonance which is often slow and requires a global system drive. Moreover, because one prerequisite for the Elzerman and Pauli spin blockade readout mechanisms typical of semiconductor spin qubits is tunneling of electrons between sites, these read-out modalities are unavailable in MSQs. Here, we theoretically demonstrate electrical read-out of entangled MSQs via driven many-electron spin unpolarized currents. In particular, using a time-dependent density matrix renormalization group approach we simulate a maximally entangled MSQ pair between two electronic leads. Driving itinerant electrons between the two leads, we find that the conductance is greater when the MSQs are in the entangled singlet state as compared to the entangled triplet state. This contrast in conductance is enhanced when the electronic density of states at the Fermi energy is large and for narrow bandwidth. Our results are readily applicable to molecules supramolecularly functionalizing semiconductors with relatively flat bands such as single-wall carbon nanotubes under a magnetic field.

cond-mat.mes-hallCross-listedarXiv:2602.21322Feb 26, 2026

Quantum Entanglement and Coherence in Molecular Magnets

Muhandis Shiddiq

Jan 1, 20150 citations

Entanglement in a molecular magnet dimer

T. Guidi, Elena Garlatti, Stefano Carretta +6 more

Bulletin of the American Physical SocietyMar 5, 20190 citations

Magnetoelectric effect in the mixed valence polyoxovanadate cage V $_{12}$ Magnetoelectric effect in the mixed valence polyoxovanadate cage V$_{12}$

Piotr Kozłowski

Development of spintronic and quantum computing devices increases demand for efficient, energy saving method of spin manipulation at molecular scale. Polyoxovanadate molecular magnets being susceptible to both electric and magnetic fields may serve here as a good base material. In this paper two isostructural anions [V $_{12}$ As $_8$ O $_{40}$ (HCO $_2$ )] $^{n-}$ (with $n=3,5$ ) featuring two different mixed-valence states with itinerant and localized valence electrons are studied. The impact of the electric field on their magnetic properties is investigated by means of two complementary methods informed by magnetic measurements: effective Hamiltonian calculations and density functional theory. It is demonstrated that the magnetoelectric effect in theses molecules is induced mostly by relocation of itinerant electrons, is highly anisotropic, depends on the valence state and can be detected even at room temperature. These findings can pave the way to practical applications in which an electric field control over spin state is required.Development of spintronic and quantum computing devices increases demand for efficient, energy saving method of spin manipulation at molecular scale. Polyoxovanadate molecular magnets being susceptible to both electric and magnetic fields may serve here as a good base material. In this paper two isostructural anions [V$_{12}$As$_8$O$_{40}$(HCO$_2$)]$^{n-}$ (with $n=3,5$) featuring two different mixed-valence states with itinerant and localized valence electrons are studied. The impact of the electric field on their magnetic properties is investigated by means of two complementary methods informed by magnetic measurements: effective Hamiltonian calculations and density functional theory. It is demonstrated that the magnetoelectric effect in theses molecules is induced mostly by relocation of itinerant electrons, is highly anisotropic, depends on the valence state and can be detected even at room temperature. These findings can pave the way to practical applications in which an electric field control over spin state is required.

cond-mat.mes-hallCross-listedarXiv:2512.02215Dec 3, 2025

Entanglement of electrons in interacting molecules

Tina A. C. Maiolo, Fabio Della Sala, L. Martina +1 more

arXiv:quant-ph/0610238Theoretical and Mathematical PhysicsAug 1, 20078 citations

Fermionic entanglement in altermagnets

Marco Kulig, Tomasz Masłowski, K. A. Kouzakov +6 more

Altermagnetism became very popular because of unique features, namely coupling between magnetic properties and momentum of itinerant electrons. The particular model of the altermagnetic system of our interest has already been studied in recent publications in a different context: . Here, we study the scattering process of an itinerant electron from the altermagnetic material on the electron localized in a GaAs quantum dot doped on the altermagnetic material. We found a spatially inhomogeneous distribution of quantum entanglement in the postscattering state. An interesting observation is the spatially anisotropic distribution of concurrence which depends on the values of the altermagnetic spin-orbit interaction constant. We also studied Rényi entropy and the effect of disorder in the system leading to randomness in the spin-orbit constant. Our main finding is that, due to the unique properties of an altermagnetic system, tuning the applied external magnetic field allows tailoring of the desired entangled state. Thus the scattering process, in essence, mimics the Hadamard-CNOT gate transformation, converting the initial disentangled state into the entangled state of Bell's state. In particular, we achieved more than 70 % fidelity between the postscattering and Bell's states.Altermagnetism became very popular because of unique features, namely coupling between magnetic properties and momentum of itinerant electrons. The particular model of the altermagnetic system of our interest has already been studied in recent publications in a different context: . Here, we study the scattering process of an itinerant electron from the altermagnetic material on the electron localized in a GaAs quantum dot doped on the altermagnetic material. We found a spatially inhomogeneous distribution of quantum entanglement in the postscattering state. An interesting observation is the spatially anisotropic distribution of concurrence which depends on the values of the altermagnetic spin-orbit interaction constant. We also studied Rényi entropy and the effect of disorder in the system leading to randomness in the spin-orbit constant. Our main finding is that, due to the unique properties of an altermagnetic system, tuning the applied external magnetic field allows tailoring of the desired entangled state. Thus the scattering process, in essence, mimics the Hadamard-CNOT gate transformation, converting the initial disentangled state into the entangled state of Bell's state. In particular, we achieved more than 70 % fidelity between the postscattering and Bell's states.

arXiv:2410.13346Physical review. B./Physical review. BMay 21, 20256 citations

Magnetoelectric effect in the mixed valence polyoxovanadate cage V

_{12}

_{12}

_8

_{40}

(HCO

_2

)]

^{n-}

(with

n=3,5

) featuring two different mixed-valence states with itinerant and localized valence electrons are studied. The impact of the electric field on their magnetic properties is investigated by means of two complementary methods informed by magnetic measurements: effective Hamiltonian calculations and density functional theory. It is demonstrated that the magnetoelectric effect in theses molecules is induced mostly by relocation of itinerant electrons, is highly anisotropic, depends on the valence state and can be detected even at room temperature. These findings can pave the way to practical applications in which an electric field control over spin state is required.