The rise of quantum mechanics in the 20th century has redefined our understanding of the universe and catalyzed revolutionary scientific and technological advancements. Today, we are on the verge of a second quantum revolution driven by quantum information science. This revolution leads us toward interdisciplinary fields like quantum-molecular biology, quantum-information thermodynamics, and quantum-causal relativity. Our research lies at the intersection of these three areas. By generalizing quantum resource theories and improving global/microscopic open system approaches, we aim to gain a deeper understanding of macroscopic phenomena such as life, energy, and time. Moreover, we are committed to developing an innovative research program inspired by this exploration, with the ambition of uncovering pathways that could lead to a prospective third quantum revolution.
The principle of quantum superposition has long been a foundational theoretical and computational tool for elucidating chemical bonds and molecular structures. Chemical bonds form when particles are shared and become delocalized across atoms or molecules. We explore particle delocalization within biomolecules and the quantum superpositions that emerge from these delocalizations, particularly from the quantum information perspective. Our research includes the examination of electron delocalization in covalent bonds [J.6, U.4], proton delocalization in hydrogen bonds [J.1, J.2, J.3], and excitation delocalization in van der Waals interactions [J.10, U.5]. The resulting superpositions reduce system energy [1] and enhance molecular stability. Additionally, based on matter-wave interferometer experiments [2], it has been suggested that these superpositions can extend to macroscopic scales within biomolecules. Moreover, the structures of molecules stabilized by chemical bonds dictate their physicochemical properties and biological functions. These observations, together with our preliminary results, lead to an intriguing question: Could nature have discovered how to generate robust and large-scale quantum superpositions long before we did and control them for the functions of biomolecules? Our research is founded on this inquiry but does not assume that the answer should necessarily be yes. Regardless of the ultimate answer, this line of inquiry could deepen our understanding of biochemical phenomena and inspire a new direction in quantum technologies. Please click here to read more about our quantum-molecular biology research
[1] F. Weinhold, J. Chem. Edu. 76, 1141 (1999); F. Weinhold and R.A. Klein, Chem. Educ. Res. Pract.15, 276 (2014).
[2] Y.Y. Fein et al., Nat. Phys. 15, 1242 (2019); A. Shayegh et al., Nat. Commun. 11, 144 (2020); F. Brand et al., Phys. Rev. Lett. 125, 033604 (2020).
There is an intricate relationship between quantum correlations and energy. Primarily, a conceptual connection exists through entropy. Thermodynamic entropy defines the relationship between the reversible transfer of heat and temperature. On the other hand, information entropy quantifies both classical and quantum correlations. Numerous examples demonstrate the equivalence of these two types of entropy. For instance, temperature can, in principle, be seen as a manifestation of quantum entanglement. Moreover, experiments [1] have shown that initial discord shared between nuclear spins can lead to an anomalous heat flow from cold to hot within a molecule. Our research agenda seeks to elucidate the intricate relationship between quantum correlations and energy, bridging quantum mechanics and thermodynamics to address fundamental questions in physics and biochemistry.
During his postdoctoral research, Onur Pusuluk derived a master equation from a microscopic collision model that describes the open system dynamics under the influence of a locally thermal environment, which can contain either classical or quantum correlations. By solving this equation analytically, regardless of the collision duration or the environment’s temperature, he identified quantum reciprocal relations between heat and quantum correlations, for which we introduced the term thermocoherent effect [J.4]. However, our quantum-information thermodynamics research is not limited to the phenomena of thermocoherence. Please click here to read more about it.
[1] K. Micadei et al. Nat. Commun. 10, 2456 (2019).
In standard quantum mechanics, the state vector of a pre-selected system provides the probability distribution for the outcomes of ideal measurements and plays a central role in the computation of the average values of physical observables. However, when the information about the pre-selected system is incomplete or less than maximal, the state vector formalism becomes inadequate. In such cases, the density matrix formalism is employed as a more comprehensive framework, capable of encoding all measurement statistics within a single mathematical construct. The density matrix, representing a statistical mixture of state vectors, contains the minimal set of parameters required to calculate the expectation values of observables. Algebraically, it is a Hermitian, positive semi-definite, and normalized operator acting on a Hilbert space. Despite its versatility, there are cases where even the density matrix formalism falls short, particularly in scenarios involving unconventional causal relationships. Examples include single systems defined by both past and future conditions [1], measurements too weak to collapse superpositions [2], quantum entanglement between temporally separated systems [3], and processes corresponding to superpositions of distinct pasts and futures [4]. Our research agenda in quantum-causal relativity seeks to address these limitations by identifying and characterizing alternative mathematical structures that can efficiently encode the measurement statistics of physical systems whose states defy representation within the conventional framework of quantum mechanics. Please click here to read more about our quantum-causal relativity research.
[1] See two-state vector formalism;
[2] See weak measurements and weak values;
[3] See quantum states over time and pseudo-density matrix/operator formalism;
[4] See indefinite causal orders and quantum SWITCH.
