Amorphous (Formula presented.) is a fundamental component of modern superconducting qubits. While amorphous oxides offer distinct advantages, such as directional isotropy and a consistent bulk electronic gap, in realistic systems these compounds also support two-level systems (TLSs) which couple to the qubit, expediting decoherence. In this work, a first-principles study of amorphous (Formula presented.) is performed and low-energy modes are identified in the electronic and vibrational spectra as a possible origin for TLSs.

We report on the induction of magnetization in Rydberg systems by means of the inverse Faraday effect and propose the appearance of the effect in two such systems: Rydberg atoms proper and shallow dopants in semiconductors. Rydberg atoms are characterized by a large orbital radius. This large radius gives such excited states a large angular moment, which when driven with circularly polarized light translates to a large effective magnetic field Beff. We calculate this effect to generate effective magnetic fields of O(1μT)×(ω1THz)-1(I10Wcm-2)n4 in the Rydberg states of atoms such as Rb and Cs for off-resonant photon beams with frequency ω and intensity I expressed in units of the denominators and n the principal quantum number. Additionally, terahertz spectroscopy of phosphorus-doped silicon reveals a large cross section for excitation of shallow dopants to Rydberg-like states, which even for small n have the potential to be driven similarly with circularly polarized light to produce an even larger magnetization. Our theoretical calculations estimate Beff as O(102T) for Si:P with a beam intensity of 108Wcm-2.

We extend the concept of conventional multiferroicity - where ferroelectric and ferromagnetic orders coexist - to include multipolar degrees of freedom. Specifically, we explore how this phenomenon emerges in 4d2/5d2 Mott insulators with strong spin-orbit and Hund's couplings. Our study uncovers the origin of magnetic multipolar interactions in these systems and demonstrates that a combination of quadrupolar and octupolar magnetic order can simultaneously induce both electrical quadrupolar moments and ferroelectric polarization. By expanding the multiferroic framework to higher-order multipoles, we reveal the possibility of coexisting multipolar orders of different or same ranks, paving the way for different functional properties in a large class of strongly correlated materials.

The mobility edge (ME) is a crucial concept in understanding localization physics, marking the critical transition between extended and localized states in the energy spectrum. Anderson localization scaling theory predicts the absence of ME in lower dimensional systems. Hence, the search for exact MEs, particularly for single particles in lower dimensions, has recently garnered significant interest in both theoretical and experimental studies, resulting in notable progress. However, several open questions remain, including the possibility of a single system exhibiting multiple MEs and the continual existence of extended states, even within the strong disorder domain. Here, we provide experimental evidence to address these questions by utilizing a quasiperiodic mosaic lattice with meticulously designed nanophotonic circuits. Our observations demonstrate the coexistence of both extended and localized states in lattices with broken duality symmetry and varying modulation periods. By single site injection and scanning the disorder level, we could approximately probe the ME of the modulated lattice. These results corroborate recent theoretical predictions, introduce a new avenue for investigating ME physics, and offer inspiration for further exploration of ME physics in the quantum regime using hybrid integrated photonic devices.

We propose to realize the quantum nonlinear Hall effect and the inverse Faraday effect through the acoustic wave in a time-reversal invariant but inversion broken Dirac insulator. We focus on the acoustic frequency much lower than the Dirac gap such that the interband transition is suppressed and these effects arise solely from the intrinsic valley-contrasting band topology. The corresponding acoustoelectric conductivity and magnetoacoustic susceptibility are both proportional to the quantized valley Chern number and independent of the quasiparticle lifetime. The linear and nonlinear components of the longitudinal and transverse topological currents can be tuned by adjusting the polarization and propagation directions of the surface acoustic wave. The static magnetization generated by a circularly polarized acoustic wave scales linearly with the acoustic frequency as well as the strain-induced charge density. Our results unveil a quantized nonlinear topological acoustoelectric response of gapped Dirac materials, like hexagonal boron nitride and transition-metal dichalcogenide, paving the way toward room-temperature acoustoelectric devices due to their large band gaps.

We propose an approach to use linearly polarized light to imprint superconducting (SC) vortices. Within the framework of the generalized time-dependent Ginzburg-Landau equations, we demonstrate the induction of the coherent vortex pairs that move in phase with electromagnetic wave oscillations. The overall vorticity of the superconductor remains zero throughout the cycle. Our results uncover rich multiscale dynamics of SC vorticity and suggest optical applications for various types of structured light. In a departure from classical laser printing, the laser printing proposed here can be viewed as quantum printing where we induce quantum excitations in the SC liquid.

The challenge of controlling the quantum states of matter via light has been at the forefront of modern research on driven quantum matter. We explore the imprinting effects of structured light on superconductors, demonstrating how the quantum numbers of light—specifically spin angular momentum, orbital angular momentum, and radial order—can be transferred to the superconducting (SC) order parameter and control vortex dynamics. Using Laguerre-Gaussian beams, we show that by tuning the quantum numbers and the amplitude of the electric field, it is possible to manipulate a variety of vortex dynamics, including breathing vortex pairs, braiding vortex pairs, vortex droplets, and swirling two-dimensional vortex rings. More complex structures of vortex clusters, such as vortex flake structures, and standing wave motions, also emerge under specific quantum numbers. These results demonstrate the ability to control SC vortex motion and phase structures through structured light, offering potential applications in quantum fluids and optical control of superconducting states. Our findings present a diagram that links light's quantum numbers to the resulting SC vortex dynamics, highlighting the capacity of light to transfer its symmetry onto superconducting condensates. We point out that this approach represents the extension of printing to quantum printing by light in a coherent state of electrons.

We investigate the interaction of a transmon qubit with a classical gravitational field. Exploiting the generic phenomena of the gravitational redshift and Aharonov-Bohm phase, we show that entangled quantum states dephase with a universal rate. The gravitational phase shift is expressed in terms of a quantum computing noise channel. We give a measurement protocol based on a modified phase estimation algorithm which is linear in the phase drift, which is optimal for measuring the small phase that is acquired from the gravitation channel. Additionally, we propose qubit-based platforms as quantum sensors for precision gravitometers and mechanical strain gauges as an example of this phenomenon's utility. We estimate a sensitivity for measuring the local gravitational acceleration to be δg/g∼10-7. This paper demonstrates that classical gravitation has a nontrivial influence on quantum computing hardware and provides an illustration of how quantum computing hardware may be utilized for purposes other than computation. While we focus on superconducting qubits, we point to the universal nature of gravitational phase effects for all quantum platforms.

We present a scanning tunneling microscopy study of room-temperature topological surface states (TSS) on Bi-terminated MnBi₂Te₄. We found that Bi-termination has a larger exchange gap than Te-termination and a higher surface magnetic ordering temperature, making it a promising system for exploring axion electrodynamics. After compensating local surface charge carriers with an electric field of the tip, we observed nontrivial current plateaus and hysteresis loops on tunnel current-voltage characteristics, which we attributed to the compressibility phase transition of TSS and induction of axion insulator quantum dot (QD). Tunneling data allowed to determine the ratio of magnetic and electric fields in QD and estimate the Chern number of a current vortex as C∼10, which suggests the formation of collective rotational resonance. We found that magnetic defects inside QD can suppress rotational resonance, as manifested either in a halt of vortex rotation or the development of Schrödinger-cat-like superpositions of rotating and non-rotating states.

Recent experiments demonstrate precise control over coherently excited circular phonon modes using high-intensity terahertz lasers, opening new pathways towards dynamical, ultrafast design of magnetism in functional materials. While the phonon Zeeman effect enables a theoretical description of phonon-induced magnetism, it lacks efficient angular momentum transfer from the phonon to the electron sector. In this work, we put forward a coupling mechanism based on electron-nuclear quantum geometry, with the inverse Faraday effect as a limiting case. This effect is rooted in the phase accumulation of the electronic wave function under a circular evolution of nuclear coordinates. An excitation pulse then induces a transient level splitting between electronic orbitals that carry angular momentum. First-principles simulations on SrTiO3 demonstrate that in parts of the Brillouin zone, this splitting between orbitals carrying angular momentum can easily reach 50 meV.