Title: experimental realisation of multi-qubit gates using electron paramagnetic resonance.

Area of Science:

• Quantum Information Science
• Molecular Spintronics
• Quantum Computing

Background:

• Quantum information processing offers significant computational advantages over classical methods.
• Molecular Electron Spin Qubits (MESQs) are promising candidates for quantum computing due to their tunable properties and potential for scalable architectures.
• Key requirements for a quantum computer include state initialization, universal quantum gates, and state measurement capabilities.

Purpose of the Study:

• To investigate the implementation of a two-qubit entangling gate on a multi-MESQ system.
• To explore methods for quantum state readout using quantum state tomography.
• To assess the feasibility of using multifrequency pulse Electron Paramagnetic Resonance (EPR) for controlling and measuring MESQ systems.

Main Methods:

• Development of a theoretical framework for performing a two-qubit entangling gate on a model MESQ system.
• Application of multifrequency pulse Electron Paramagnetic Resonance (EPR) techniques for gate operations.
• Utilisation of quantum state tomography for readout of the entangled qubit states.
• Modeling of a two-MESQ system composed of two nitroxide spin centers.

Main Results:

• Confirmation of the methodological principles for executing controlled entanglement on MESQs.
• Demonstration of a viable approach for performing a two-qubit entangling gate using EPR.
• Successful application of quantum state tomography for readout in the model system.
• Identification of experimental challenges for realizing controlled entanglement in MESQ systems.

Conclusions:

• The proposed EPR-based methods are theoretically sound for achieving controlled entanglement in MESQ systems.
• Further experimental work is needed to overcome identified hurdles and demonstrate entanglement experimentally.
• This study provides a roadmap for advancing MESQ-based quantum computing.