Research

Spin Chemistry for Quantum Applications

Quantum BIT (Qubit). The basic unit of information in quantum information science and technology (QIST). A qubit relies on a sensitive superposition consisting of both states 0 and 1, allowing it to represent a range of values simultaneously. This superposition is represented by the equation ψ = α|0⟩ + β|1⟩, where α and β are complex numbers that represent the amplitudes of the |0⟩ and |1⟩ states, where |α|² + |β|² = 1.A Bloch sphere diagram illustrating the quantum state of a qubit. The sphere is labeled with the basis states |0⟩ at the top, |1⟩ at the bottom, |+i⟩ to the right, and |-i⟩ to the left, with |+⟩ and |–⟩ on the equator. An orange arrow points from the center to a point on the sphere, representing a specific qubit state |ψ⟩, which is also shown outside the sphere. Below the sphere is the quantum eigenvalue equation Ĥ|ψ⟩ = E|ψ⟩, with the letter ψ stylized as a cactus. This image visually complements the legend explaining qubits and their superposition.

Molecular Qubits

Molecular qubits take the fundamental concept of a quantum superposition of |0⟩ and |1⟩ states and encode it directly into the structure of individual molecules. Rather than engineering quantum states in solid-state devices, trapping atoms with complex laser systems, or photon-fields, molecular qubits harness the intrinsic quantum properties that molecules naturally possess such as electron or nuclear spins. This means we can use the precision tools of synthetic chemistry to literally design and build quantum systems from the ground up.

What makes this molecular approach so powerful? Traditional quantum systems often require extreme conditions: near absolute zero temperatures, ultra-high vacuum, or complex cleanroom fabrication. Molecular qubits, by contrast, can be chemically tailored to optimize their quantum behavior by modifying ligand environments, adjusting the molecular geometry, tuning orbital overlap, or enhancing luminescence.

The potential for molecular qubits is immense with the versatility and scalability chemistry brings. Molecular qubits can operate under milder conditions than many alternatives, making them particularly attractive for quantum sensing applications where you need to detect magnetic fields, temperature changes, or chemical environments in real-world settings. Plus, synthesizing millions of identical molecules is routine chemistry, opening pathways to scalable quantum technologies.

Earley Lab's Approach to Quantum Information Science and Technology (QIST)

Research in the Earley Lab focuses on understanding and controlling molecular qubits at multiple levels. We investigate intramolecular effects such as how the internal structure and electronic environment of individual molecules influence their quantum properties. We study intermolecular effects such as exploring how molecular qubits interact with each other and their surroundings, including the development of molecular qubit arrays for creating entangled quantum systems. Additionally, we develop advanced magnetic spectroscopy techniques to probe and characterize these quantum states with unprecedented precision. Lastly, we apply quantum sensors to study chemical systems, probing electron, energy, and ionic transport processes as well as molecular configuration and identity.

Illustration showing clusters of orange molecules with wavy gray lines radiating outward, representing molecular structures. Overlapping this is a second circle depicting a central purple and green spiral structure surrounded by gray spheres connected in a network, symbolizing a complex molecular or intramolecular system.

Structure-Function Relationships in Molecular Qubits

Understanding the quantum properties of molecular qubits requires detailed analysis of how intramolecular electronic structure parameters directly influence spin coherence mechanisms and sensitivity. Our research investigates how factors such as spin orbit coupling strength, crystal field splitting, and hyperfine interactions with nuclear spins determine relaxation dynamics across diverse molecular platforms including coordination complexes, organic color centers, and defects in macromolecular systems. We examine how molecular orbital composition and electronic structure affect the coupling of spins to phononic and intramolecular noise sources that drive decoherence processes within individual molecules.

A key focus involves optimizing initialization and readout pathways through control of intersystem crossing rates and luminescence quantum yields in these varied molecular architectures. Using a comprehensive suite of electron paramagnetic resonance (EPR), optically detected magnetic resonance (ODMR), photophysical, and magnetic spectroscopies, we study how structural parameters influence optical transitions, spin phonon coupling coefficients, electron polarization, and coherent mixing. By correlating computational predictions of electronic structure with experimental measurements, we develop quantitative relationships that enable rational design of molecular qubits with enhanced intramolecular performance metrics.

Diagram featuring two overlapping circles. The lower left circle shows a hexagonal lattice pattern with blue and green quantum spins and swirling orange lines, representing quantum effects in a 2D material. The upper right circle displays a molecular structure on a similar lattice, with blue and green quantum spins and attached molecules, illustrating functionalized 1D or 2D materials.

Collective Quantum Phenomena in Molecular Networks

Understanding how molecular qubits behave in networked environments requires investigation of intermolecular interactions and external environmental factors that influence quantum coherence and entanglement. Our research focuses on qubit bath dynamics, examining how molecular qubits couple to their surrounding environment through mechanisms such as dielectric coupling, vibrational modes, and electromagnetic field fluctuations. We study how macroscale organization and molecular packing arrangements affect spin coherence times and sensitivity, providing insights into designing quantum materials that maintain coherence under realistic operating conditions rather than the ultra-high vacuum and cryogenic environments typically required for traditional quantum systems.

A particularly exciting aspect of this work involves utilizing one-dimensional and two-dimensional molecular materials as platforms for studying quantum entanglement and collective spin phenomena. By leveraging molecular level synthetic control, we can systematically tune intermolecular distances, coupling strengths, and network topologies to create entangled qubit arrays. These molecular networks allow us to test fundamental questions about quantum resilience, decoherence mechanisms, and many-body quantum effects under ambient or near ambient conditions. This approach opens pathways toward practical quantum technologies that operate in real-world environments while maintaining the precision control that only molecular design can provide.

Two overlapping circles. The left circle shows a biological cell or sample on a surface, with rainbow-colored wavy arrows indicating light or spectroscopy signals. The right circle depicts a blue and green quantum spin between two large gray magnets labeled N and S, with orange magnetic field lines, representing quantum sensing or spectroscopy in a magnetic field.

Advanced Quantum Characterization Methods

Advancing the field of molecular quantum information science requires the development of sophisticated spectroscopic and magnetic resonance techniques that can probe quantum phenomena with unprecedented precision and sensitivity. Our instrumentation development efforts focus on creating new methods to directly investigate the relationships between optical and electron spin dynamics in molecular qubits, enabling real-time monitoring of quantum state evolution and coherence processes. We design and build custom spectrometers that combine optical excitation with magnetic resonance detection, allowing us to map how photophysical processes influence spin states and vice versa.

We are interested in developing techniques to probe structural chirality and its connection to electron spin polarization, opening new avenues for understanding how molecular asymmetry affects quantum properties. Additionally, we consider consumer deployable quantum sensing instrumentation that leverages molecular qubits for practical applications outside traditional laboratory settings. These portable quantum sensors can detect magnetic fields, temperature variations, and chemical environments with quantum-enhanced sensitivity, making advanced quantum technologies accessible for field applications, industrial monitoring, and distributed sensing networks.

Illustration with two overlapping circles. The lower left circle shows many red nanoparticles with yellow strands, and a central blue and green quantum spin surrounded by orange field lines. The upper right circle features red sodium ion (Na⁺) symbols and a blue and green quantum spin with orange field lines, representing quantum sensing in ionic or nanoparticle environments.

Quantum Sensing of Chemical Structure and Dynamics

The exceptional sensitivity and precision of quantum sensors opens unprecedented opportunities to probe fundamental chemical processes at the molecular level. Our research applies established quantum sensing platforms, particularly nitrogen vacancy (NV) diamond centers, to investigate chemical physics phenomena including molecular structure determination, ion transport pathways, electron transfer kinetics, and energy transfer dynamics. By leveraging the nanoscale spatial resolution and magnetic field sensitivity of quantum sensors, we can monitor chemical processes with few-molecule sensitivity, revealing details about charge transport mechanisms, and energy flow that can be inaccessible to conventional analytical techniques.

This work simultaneously pushes the boundaries of quantum sensing applications while advancing our fundamental understanding of chemical systems. We develop new protocols for using quantum sensors to map local electric and magnetic field environments around reactive sites, track the movement of charged species through materials, and monitor energy transfer processes in biological and synthetic systems. These quantum-enhanced measurements provide insights into chemical dynamics that inform the design of more efficient catalysts, better energy storage materials, and improved drug delivery systems. By demonstrating the utility of quantum sensing across diverse chemical applications, we establish new paradigms for chemical analysis and deepen our understanding of the quantum mechanical foundations underlying chemical phenomena.