Physical Review Research

This Perspective outlines a staged road map for building a fault-tolerant quantum computer based on topologically protected Majorana-based qubits. The plan spans several device generations, from a single-qubit device used for qubit benchmarking, a two-qubit device for a measurement-based braiding operation, and an eight-qubit device for quantum error detection to extended qubit lattices that support universal logical operations at scale. Key design elements, operating protocols, and the advantages of this approach for scalable, utility-scale quantum computation are highlighted.

A viscoelastic model is developed in which a biomolecular condensate is a composite of viscous and elastic mesoscopic elements connected in series and in parallel, unifying the Maxwell and Jeffreys descriptions as limiting cases. The model indicates that aging of PGL-3 condensates stems from the conversion of viscous elements into two types of elastic ones, leading to exponential or power-law growth of the viscosity with waiting time.

An exactly solvable multispecies spherical spin model is introduced to study the collective equilibrium states of swarmalators, mobile oscillators with coupled spatial and phase degrees of freedom. A unified description of the resulting hierarchy of states, their transitions, and their fundamental relationship to noisy Kuramoto dynamics is provided.

An optimal pathway to ultracold ${}^{86}$Sr${}_2$ is identified and implemented, enabling the production of stable samples of halo molecules. Their vibrational binding energies, which are exceptionally sensitive to internuclear forces at nanometer length scales, are measured using hertz-level precision spectroscopy.

First-principles, tight-binding, and $\mathbf{k}$ $\cdot$ $\mathbf{p}$ calculations are used to examine how strain and quantum confinement affect the electronic topology of wurtzite HgTe. The study relates bulk Dirac points along the wurtzite $c$ axis to strain-dependent phases, orientation-dependent thin-film topology, and edge-localized states in nanowires.

The Doppler-residual line shape that limits the linewidth of a two-photon Rydberg electromagnetically induced transparency in a thermal vapor is derived. The Doppler-limited energy resolution of the Rydberg state is found to be 1.84 MHz in ${}^{85}$Rb, a linewidth of 2.04 MHz is experimentally measured, and the broadening mechanisms near this limit are characterized.

Correlations between consecutively emitted pulses in quantum key distribution transmitters violate the assumptions underlying many security proofs. This problem is addressed by showing that security proofs based on phase-error estimation developed for imperfect but uncorrelated sources can be directly extended to incorporate such correlations.

In a disorder-free non-Hermitian lattice with an entirely real spectrum and without any external force, a moving wave packet can exhibit sudden jumps or oscillations. Near a boundary, a wave packet can reflect with delay or advance in time, which is the temporal analogue of the Goos-Hänchen shift.

Optically addressed ensembles of qubits offer scalable control through global operations. Motivated by these platforms, robust composite pulse sequences are introduced that realize arbitrary site-dependent single-qubit unitaries in parallel using global pulses and requiring only minimal individual control.

The strong asymmetry of Autler-Townes doublets in intense-field ionization has been attributed to either interfering ionization pathways or strong-field dressing of the continuum. These seemingly distinct interpretations are here shown to arise from a time-dependent effective Hamiltonian formalism, which is demonstrated to reproduce $ab$ $initio$ photoelectron spectra.

It is shown on the example of a honeycomb ferromagnet that spin inertia hybridizes the precessional and nutational magnon bands, opening a topologically nontrivial gap whose size scales linearly with the strength of pseudodipolar interaction. Chern number calculations and spectra calculated in a slab geometry demonstrate the emergence of chiral edge modes within this gap.

Fractional Chern insulators are generally associated with topologically nontrivial bands. Here, it is demonstrated that realistic Coulomb interactions stabilize a Laughlin-like fractional Chern insulator in a trivial ($C$ = 0) moiré band, revealing how quantum geometry can enable many-body topology without band topology.

This article presents dynamical measurements of quantum geometry for systems with noncompact SU(1,1) symmetry via double quench in parameter space.

Measurement-feedback control of driven-dissipative quantum batteries in waveguide-QED systems is investigated. The feedback enables perfect charging without coherent driving for a single-atom battery and, together with collective effects, generates a boundary time-crystal phase with persistent energy oscillations and two stationary charging phases in many-body battery arrays.

The correlation-induced localization, that is, the Anderson localization in long-range models with correlated hopping, is found to be robust to time-reversal symmetry (TRS) breaking up to a certain critical TRS breaking parameter. It is also shown that, unlike eigenstate localization properties, the wave-packet dynamics is fragile to any TRS breaking and undergoes a transition from subdiffusion at TRS to diffusion otherwise.

While pushing is intuitively associated with progress, it can surprisingly cause tracers moving in disordered environments to become permanently confined. This study shows that confinement is a result of irreversible “door-closing” events, providing a minimal description of pushing-induced arrest across lattices and dimensions.

Dynamic trapping and manipulation of floating particles using reconfigurable water-wave interference patterns is demonstrated. By controlling the phases or frequencies of the interfering waves, transport of one or two particles along arbitrary prescribed trajectories is achieved.

A geometric control framework is presented that leverages a parameterized metric space to smoothly interpolate between diabatic and adiabatic quantum dynamics for state transfer in multilevel systems. By mapping single-parameter pulse shaping to routing along geometric trajectories, the method enables high-fidelity quantum information processing.