A transmon qubit embedded in a high-impedance environment acts in a way dual to a conventional Josephson junction. In analogy to the AC Josephson effect, biasing of the transmon by a direct current leads to the oscillations of voltage across it. These oscillations are known as the Bloch oscillations. We find the Bloch oscillations spectrum, and show that the zero-point fluctuations of charge make it broadband. Despite having a broad-band spectrum, Bloch oscillations can be brought in resonance with an external microwave radiation. The resonances lead to steps in the voltage-current relation, which are dual to the conventional Shapiro steps. We find how the shape of the steps depends on the environment impedance R, parameters of the transmon, and the microwave amplitude. The Bloch oscillations rely on the insulating state of the transmon which is realized at impedances exceeding the Schmid transition point, R > R = h/(2e).
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http://dx.doi.org/10.1038/s41467-025-56411-x | DOI Listing |
Nat Commun
February 2025
Department of Physics and Center for Quantum Materials, The Hong Kong University of Science and Technology, Hong Kong, China.
Two-dimensional electron systems in both magnetic fields and periodic potentials are described by the Hofstadter butterfly, a fundamental problem of solid-state physics. While moiré systems provide a powerful method to realize this type of spectrum, previous experiments have been limited to fractional flux quanta regime, due to the difficulty of building ~ 50 nm periodic modulations. Here, we demonstrate a super-moiré strategy to overcome this challenge.
View Article and Find Full Text PDFPhys Rev Lett
February 2025
Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany.
Quantum simulations of Hubbard models with ultracold atoms rely on the exceptional control of coherent motion provided by optical lattices. Here we demonstrate enhanced tunability using an optical superlattice in a fermionic quantum gas microscope, evidenced by long-lived coherent double-well oscillations, next-nearest-neighbor quantum walks in a staggered configuration, and correlated quantum walks of two particles initiated through a resonant pair-breaking mechanism. We furthermore demonstrate tunable spin couplings through local offsets and engineer a spin ladder with ferromagnetic and antiferromagnetic couplings along the rungs and legs, respectively.
View Article and Find Full Text PDFNat Commun
February 2025
Department of Physics, Yale University, New Haven, CT, 06520, USA.
A transmon qubit embedded in a high-impedance environment acts in a way dual to a conventional Josephson junction. In analogy to the AC Josephson effect, biasing of the transmon by a direct current leads to the oscillations of voltage across it. These oscillations are known as the Bloch oscillations.
View Article and Find Full Text PDFNeural Netw
May 2025
Department of Mathematical Sciences, Rajiv Gandhi Institute of Petroleum Technology, Jais, Amethi, Uttar Pradesh, 229304, India. Electronic address:
In this paper, we introduce the concept of (ω,c)-asymptotic periodicity within the context of translation-invariant time scales. This concept generalizes various types of function, including asymptotically periodic, asymptotically antiperiodic, asymptotically Bloch periodic, and certain unbounded functions on time scales. We investigate some fundamental properties of this class of functions and apply our findings to cellular neural network (CNN) dynamic equations with leakage and mixed time-varying delays.
View Article and Find Full Text PDFHere we experimentally demonstrate the dynamics of Bloch-Zener oscillations (BZOs) in a synthetic temporal lattice formed by the optical pulses in coupled fiber loops. By periodically modulating the phases imposed to the optical pulses in linear driven lattices, a two-band Floquet system with tunable bandgaps is realized, and the related BZOs that occurred in this system are displayed. On this basis, by manipulating the phase difference and coupling angle of the synthetic lattice, the widths of 0-gap and -gap are tuned feasibly so that a wide variety of the interplays between Bloch oscillations and Landau-Zener tunneling (LZT) are exhibited.
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