Quantum computation based on resonance transition

Chen-Fu Chiang, Chang‐Yu Hsieh

Lin Tian, Seth Lloyd

Off-resonant effects are a significant source of error in quantum computation. This paper presents a group-theoretic proof that off-resonant transitions to the higher levels of a multilevel qubit can be completely prevented in principle. This result can be generalized to prevent unwanted transitions due to qubit-qubit interactions. A simple scheme exploiting dynamic pulse control techniques is presented that can cancel transitions to higher states to arbitrary accuracy.

Lov K. Grover, Murray Hill, New Jersey

G. P. Berman, G. D. Doolen, V. I. Tsifrinovich

Pan, Bo-Syun, Yen‐Hsiang Lin, Chiao-Hsuan Wang

Dispersive readout plays a central role in superconducting quantum computing, enabling quantum nondemolition measurements through a coupled microwave resonator. While stronger resonator drives can improve measurement speed and fidelity, they can also activate multi-photon resonances that trigger measurement-induced state transitions (MIST) out of the computational subspace. We develop a driven-dissipative framework for MIST that retains the quantum resonator response absent in semiclassical treatments and yields analytically derived transition-rate expressions. The upward and downward transition-rate profiles determine the steady-state populations and finite-time dynamics, enabling quantitative exploration across drive strength and detuning, while capturing the crossover between quantum-resolved and semiclassical-like dynamics. This framework reproduces the quantum dynamics and identifies a strongly driven regime beyond semiclassical Landau--Zener predictions, where delayed population transfer opens a finite-time readout window with high resonator photon population. These results establish MIST as a predictive driven-dissipative process and characterize strongly driven regimes that can be leveraged for measurement optimization.

Majed S. Fataftah, Joseph M. Zadrozny, Scott C. Coste +3 more

The implementation of quantum computation (QC) would revolutionize scientific fields ranging from encryption to quantum simulation. One intuitive candidate for the smallest unit of a quantum computer, a qubit, is electronic spin. A prominent proposal for QC relies on high-spin magnetic molecules, where multiple transitions between the many MS levels are employed as qubits. Yet, over a decade after the original notion, the exploitation of multiple transitions within a single manifold for QC remains unrealized in these high-spin species due to the challenge of accessing forbidden transitions. To create a proof-of-concept system, we synthesized the novel nuclear spin-free complex [Cr(C3S5)3](3-) with precisely tuned zero-field splitting parameters that create two spectroscopically addressable transitions, with one being a forbidden transition. Pulsed electron paramagnetic resonance (EPR) measurements enabled the investigation of the coherent lifetimes (T2) and quantum control (Rabi oscillations) for two transitions, one allowed and one forbidden, within the S = (3)/2 spin manifold. This investigation represents a step forward in the development of high-spin species as a pathway to scalable QC systems within magnetic molecules.