There are several important solid-state systems, such as defects in solids, superconducting circuits and molecular qubits, for attractive candidates of quantum computations. Molecular qubits, which benefit from the power of chemistry for the tailored and inexpensive synthesis of new systems, face the challenge from decoherence effect. The decoherence effect is due to the molecular qubits' inevitable interactions to their environment. Strategies to overcome decoherence effect have been developed, such as designing a nuclear spin free environment and working at atomic clock transitions. These chemical approaches, however, have some fundamental limitations. For example, chemical approach restricts the ligand selection and design to ligands with zero nuclear magnetic dipole moment, such as carbon, oxygen, and sulfur. Herein, a physical approach, named Dynamical decoupling (DD), is utilized to combat decoherence, while the limitations of the chemical approaches can be avoided. The phase memory time
T2 for a transition metal complex has been prolonged to exceed one millisecond (
1.4 ms) by employing DD. The single qubit figure of merit $Q_M $ reaches $ 1.4\times 10^5$, which is
40 times better than that previously reported value for such system. Our results show that molecular qubits, with milliseconds
T2, are promising candidates for quantum information processing.
Molecular qubits, owing to their designability and tunability, have emerged as fundamental units for quantum technologies. Among them, molecular qubit frameworks (MQFs) offer unique advantages in long-range ordered lattices and microporosity that provide well-defined phonon environments and guest-tunable spin dynamics. These features greatly enhance qubit performance and enable room temperature quantum operations, holding promise for quantum sensing applications. Herein, we compare the qubit performance of 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) and tetrathiafulvalene tetrabenzoic acid (H4TTFTB), which form stable radicals upon spontaneous oxidation in the air. We found that optical phonons dominate spin relaxation in HHTP, whereas H4TTFTB exhibits stronger spin-orbit coupling and higher acoustic phonon population that account for its shorter spin relaxation time. Meanwhile, H4TTFTB features a nuclear-spin-free core and in turn a prolonged phase memory time, making it a favorable qubit candidate. Furthermore, we synthesized three MQFs using H4TTFTB as the ligand, which not only retain the superior room-temperature qubit performance but also possess porous channels, establishing a viable platform for future quantum information applications.
ABSTRACT This review classifies qubit platforms from the perspective of quantum battery applications as inorganic, molecular, and organic material families using an energy‐based approach. The systems are compared in terms of energy level tunability, decoherence mechanisms, and environmental sensitivity. Superconducting and silicon spin qubits stand out with their high control accuracy and long decoherence times (on the order of seconds in purified silicon); however, the need for cryogenic operation and fixed energy levels limits them. In contrast, molecular (lanthanide and transition‐metal complexes) and organic (radical/polymer) systems offer atomically precise tunable energy levels through ligand engineering and chemical design and operate under near‐room temperature conditions. The study evaluates qubit platforms not only in terms of information processing but also with battery‐focused metrics such as energy capacity, charge power, ergotropy, storage lifetime, and quantum advantage arising from entanglement and collective interactions. Thus, molecular and organic systems stand out as the most promising candidates for quantum batteries due to their chemical tunability and bulk charging potential; the study presents a materials‐based roadmap combining quantum computing with energy storage.
The coordination complexes of Yb(III) exhibit some of the longest spin coherence times among 4f compounds, making them a promising platform for molecular quantum technologies. While spin-phonon relaxation remains a limiting factor for coherence times even at low temperature, its control through chemical design has the potential to push these spin qubits prototypes beyond current limits. With the aim of providing insights on how to chemically control spin-phonon relaxation, we here present a full ab initio study of spin-phonon dynamics for three Yb(III) molecules exhibiting minimal chemical differences, yet quantitatively different spin relaxation times. Results show that low-temperature relaxation is governed by Raman processes triggered by a small group of largely delocalized low-energy phonons. The analysis of these contributions highlights that the modulation of spin-phonon coupling by molecular structure modifications beyond the first coordination shell are highly non-trivial in nature and hard to rationalize in simple chemical terms. These findings call for a conceptual step change from the attempt to use simple magneto-structural correlations to interpret the effect of molecular structural modifications on spin-phonon relaxation, and present predictive first-principles frameworks as a potential driving force of future chemical design strategies