Key Scientific Concepts
What are the molecular degrees of freedom that CMQT seeks to understand?
Molecular systems are exciting candidates for quantum information hardware, particularly for the transduction - or conversion - of one form of information to another. Molecules can be designed and tailor-fit to desired specifications, then manipulated into a variety of environments: placed next to solid-state qubits, deposited in a thin film, or embedded into photonic structures. The ability to transduce information between external excitations or a molecule’s natural properties is essential to realizing a diversity of quantum information architectures.
Solid-state electronic spins suffer a rigid set of limitations regarding phase memory coherence times (T2) and scalability. Conversely, molecular spin qubits benefit from the flexibility of ligand chemistry to design around such limitations.
Organometallic molecules could be synthesized to optimize the response to a specific external stimulus or linked together to form larger logical units. The spin states can be tuned into or out of interaction with other localized quantum objects.
A key step in lengthening coherence times for molecular spin qubits is understanding the effects of magnetic noise from nearby nuclear and electronic spins. Insights gained from studies done previously on established solid-state quantum systems, such as nitrogen-vacancy centers, provide a roadmap to characterizing the constrains on molecular spin qubits.
“Flying qubits” – or photons – are a requisite component to quantum networks. Photons can be transmitted using existing optical fiber telecommunication infrastructure; existing stationary quantum systems (nitrogen vacancy centers, quantum emitters in 2D materials, and even molecules) are not particularly good at coupling with photons at the telecommunication wavelength O- and C-bands.
Thus, light-matter interactions are important to investigate theoretically and experimentally. When designed for transduction purposes, photonic structures – normally used to enhance coupling – can instead tune the light-matter interaction strength and control their hybridized modes. Novel nanomaterials provide increasing opportunity to study polaritons as a mediator between flying and stationary quantum objects.
Molecule-based magnetic materials provide low-damping modes for collective spin excitations – or magnons – to couple with microwave-frequency quantum objects, such as superconducting resonators.
These organic-based materials have advantages over traditional magnetic materials like yttrium iron garnet. The ability to use thin-film techniques to pattern ferromagnetic materials, such as vanadium tetracyanoethylene, gives flexibility in the architecture that physically connects disparate quantum objects and lends control over their interactions.
In particular, certain organic-based materials can be built around tailored molecular spin qubits in order to maximize coupling. In this method, a single spin state is communicated to a distributed quantum system.