Research

We develop schemes for quantum information processing exploiting Molecular spin systems (and in particular Molecular Nanomagnets) as elementary units. Typically, these systems are highly enineerable at the synthetic level and display many low-energy levels which can be coherently manipulated with high accuracy. Hence, they naturally provide qudits for quantum logic. The most important possibility is to encode in molecular spins quantum bits with embedded quantum error-correction, a mandatory step to realize a scalable quantum hardware.

See our most relevant publications on this topic:

• Embedding quantum-error correction within individual molecules: [1], [2], [3]
• A fault-tolerant scheme for universal quantum computing on molecular spin qudits protected from dephasing: pre-print at [4]   
• Suppressing decoherence and qudit-size dependence by spin-Hamiltonian engineering: [5], [6];  
• Dynamically switching the qubit-qubit coupling in chains of permanently coupled qubits (with molecules from University of Manchester and Florence): [7], [8], [9]
• Proposals for quantum simulation of closed [9], [10] and open [11], [12] quantum systems (with molecules from University of Manchester and Florence)
• First proof-of-concept quantum simulator on a nuclear spin qudit (with molecules from University of Copenhagen): pre-print at [13] 
• Blueprint of a molecular spin quantum processor (with University of Zaragoza and CSIC): [14]
• Reviews, perspectives: [15] 

Activity carried on within the NQSTI project.

[Image made by Simone Riccardi]

This research theme proceeds along two parallel lines: on the one hand we develop theoretical models to understand Chirality-Induced Spin Selectivity in electron transfer processes through a chiral bridge. This is done by combining targeted properly designed (magnetic resonance) experiments with a microscopic description of the phenomenon (also with the help of ab-initio calculations). On the other hand, we design schemes exploiting CISS as an enabling technology for quantum applications. These are related, in particular, to initialization and readout of individual molecular spin qubits, implementation of two-qubit entangling gates, quantum sensing. 

Most relevant results on the topic:

• Understanding the origin of CISS by magnetic resonance experiments: design [1] (with Freie Universitat Berlin) and interpretation of experiments [2] (with University of Florence, Turin, Bologna, Pisa), [3]
• First observation of CISS in isolated molecules by time-resolved EPR [3] (with Northwestern University)
• Modeling Electron-Transfer reactions with spin-selective Haberkorn formalism [4] (with Freie Universitat Berlin) 
• CISS as an enabling tool for quantum technologies, and in particular for high-temperature initialization and readout of individual spins [5] (with University of Florence, Freie Universitat Berlin, Northwestern University and Weizmann Institute).

Research activity carried on within the ERC-Synergy CASTLE project.

[Image made by Simone Riccardi]

Molecular Nanomagnets are protypical systems to investigate fundamental quantum phenomena. We do this by designing targeted experiments and combining them with sound theoretical models. 

Most important research topics:

• Probing entanglement by Inelastic Neutron Scattering [1]
• Coherent spin dynamics unveiled by Inelastic Neutron Scattering [2] 
• Fingerprints of the spin Hamiltonian by 4D-Inelastic Neutron Scattering [3]
• Accessing phonon states and their role in modulating spin relaxation [4]
• Spin frustration unravelled by Inelastic Neutron Scattering [5]
• Theoretical models for decoherence of molecular spins [6]
• Origin of magnetic interaction from many-body ab-initio models [7]

• Characterization of molecular spin qudits by Nuclear Magnetic Resonance
• 4-dimensional Inelastic Netron Scattering (INS) as fingerprint of the magnetic Hamiltonian and to unravel the spin dynamics
• X-ray scattering to access the phonon spectrum

[Figure: 4D INS spectrum of Mn₁₂, the forefather of Molecular Nanomagnets, unravelling the structure of its eigenstates. Reprinted with permission from Phys. Rev. Lett. 119, 217202 (2017), Copyright(2017) by the American Physical Society]