Research Projects

Organic radicals are of tremendous interest to realize functional properties that is intrinsic to its unpaired electronic-spin [1-3] resulting in attractive conductivity and magnetic properties. While these properties from radicals and radical ions are known for past several decades, a new possibility is being envisaged that evolves from electron-spin and has wide implications in quantum-based applications [7]. This is since spin is intrinsically a two-level quantum system and can easily be manipulated by electromagnetic radiations. In this context, quantum information processing (QIP) can potentially transform the present digital landscape and steer in a second information age [8]. QIP differs from its classical analogue that exist in one of two states 0 or 1 (classical bits), whereas quantum bits (qubits, basic unit of quantum information) can be placed into a quantum superposition, thereby simultaneously accessing multiple states. Thus, ongoing research has resulted in new qubit candidates [9-16]. Research Background and Gap Area: Although at a nascent stage of development, molecular qubits are presumed to be vastly advantageous for QIP than other qubit candidates as it is synthetically tailorable and provide atomistic control to regulate electron-spin and electron-nuclear spin interactions. According to DiVincenzo’s criteria, physical implementation of qubit requires two-level quantum systems to be: highly coherent, initializable, controllable, measurable, and scalable [17]. Most importantly, for QIP applications it is a prerequisite that molecular qubits maintain long coherence times during quantum manipulation and readout. The molecular qubits reported till date have been constructed majorly from metal complexes [18-24], there are only few reports of organic neutral radical based qubits [25], while organic radical ions have been very scarcely investigated as molecular qubits [26]. The quantum coherence time (Tm) realized with metal complexes can reach up to tens of microseconds (µs), while neutral radicals, with only few exceptions have Tm predominantly shorter than µs. However, the radical ions studied for quantum coherence have very short coherence times and have stability issues. All these provides a vast scope to design and synthesize new radical ion-based qubits with long coherence times and seek for controlled spin-transport for associated quantum function. Our experience with Organic Radicals and Preliminary Results: Over the years, we have made significant progress in the design, synthesis and isolation of diverse types of stable radical ions [27-34]. In this proposal, we wish to further take forward the design and synthetic aspect of the radical ions by implementing atomistic control of electron- and nuclear-spin hyperfine interactions, spin diffusion barrier, etc. to realize molecular qubits. We believe by controlling these parameters and with our prior experience on functional molecular materials [35-46], we can achieve new generation of multifunctional radical ions with long quantum coherence times for qubit applications. Our preliminary results with synthesized radical ions and neutral radicals demonstrate quantum coherence time can be achieved up to a few µs. Importantly, the quantum coherence time can be sustained not only at cryogenic temperatures, but importantly, even at room temperatures, which is rare with the existing molecular qubits. Novelty and anticipated impact: Highly contemporary area of research; Not yet taken up Nationally and very few examples of radical-based qubits with long coherence times; Vast experience in radical design, synthesis, stabilization, EPR spectroscopy; A Collaborative and Unique project with an expert in fabrication of molecular electronic devices that aim to explore various realms of molecule-based quantum function.