We benchmark the decoherence of superconducting qubits to examine temporal stability energy-relaxation and dephasing. By collecting statistics during measurements spanning multiple days, we find mean parameters $\overline{T_{1}}$ = 49 $\mu$s $\overline{T_{2}^{*}}$ 95 $\mu$s, however, both these quantities fluctuate explaining need for frequent re-calibration in qubit setups. Our main finding is that fluctuations relaxation are local caused by instabilities near-resonant two-level-systems...

Hosting nonclassical states of light in three-dimensional microwave cavities has emerged as a promising paradigm for continuous-variable quantum information processing. Here we experimentally demonstrate high-fidelity generation range Wigner-negative useful computation, such Schrödinger-cat states, binomial Gottesman-Kitaev-Preskill well cubic phase states. The latter have been long sought after optics and never achieved before. We use sequence interleaved selective number-dependent...

Engineering the electromagnetic environment of a quantum emitter gives rise to plethora exotic light-matter interactions. In particular, photonic lattices can seed long-lived atom-photon bound states inside band gaps. Here we report on concept and implementation novel microwave architecture consisting an array compact, high-impedance superconducting resonators forming 1 GHz-wide pass band, in which have embedded two frequency-tuneable artificial atoms. We study atom-field interaction access...

Abstract Superconducting qubits are among the most advanced candidates for achieving fault-tolerant quantum computing. Despite recent significant advancements in qubit lifetimes, origin of loss mechanism state-of-the-art is still subject to investigation. Furthermore, successful implementation error correction requires negligible correlated errors between qubits. Here, we realize long-lived superconducting transmon that exhibit fluctuating averaging 0.2 ms and exceeding 0.4 – corresponding...

The reproducibility of qubit parameters is a challenge for scaling up superconducting quantum processors. Signal cross talk imposes constraints on the frequency separation between neighboring qubits. uncertainty transmon qubits arising from fabrication process attributed to deviations in Josephson junction area, tunnel barrier thickness, and shunt capacitor. We decrease sensitivity these variations by fabricating larger junctions reduce wafer-level standard deviation resistance down 2%....

Exploiting multiple modes in a quantum acoustic device could enable applications information hardware-efficient setup, including simulation synthetic dimension and continuous-variable computing with cluster states.We develop multimode surface wave (SAW) resonator superconducting interference (SQUID) integrated one of the Bragg reflectors. The interaction SQUID-shunted mirror gives rise to coupling between more than 20 accessible modes. We exploit this demonstrate two-mode squeezing SAW...

Niobium nitride ($\mathrm{Nb}\mathrm{N}$) is a particularly promising material for quantum technology applications, as it shows the degree of reproducibility necessary large-scale superconducting circuits. We demonstrate that resonators based on $\mathrm{Nb}\mathrm{N}$ thin films present one-photon internal quality factor above ${10}^{5}$ maintaining high impedance (larger than $2\mathrm{k}\mathrm{\ensuremath{\Omega}}$), with footprint approximately...

Vacuum gap capacitors have recently gained considerable attention in superconducting circuit platforms due to their compact design and low dielectric losses the microwave regime. Their ability support mechanical vibrational modes makes them ideal candidates for optomechanics. However, precise control of size achieving high coherence remain long-standing challenges. Here, we present a detailed fabrication process scalable vacuum that ultra-high-coherence motion, exhibit loss, maintain small...

Quantum metrology, a cornerstone of quantum technologies, exploits entanglement and superposition to achieve higher precision than classical protocols in parameter-estimation tasks. When combined with critical phenomena such as phase transitions, the divergence fluctuations is predicted enhance performance sensors. Here, we implement sensor using superconducting parametric (i.e., two-photon driven) Kerr resonator. The sensor, linear resonator terminated by interference device, operates near...

A novel type of thermometer provides a simple, fast, and accurate means to monitor the temperature propagating microwave modes, providing benchmarking tool for quantum computing enabling experiments in thermodynamics.

We numerically and experimentally investigate the phononic loss for superconducting resonators fabricated on a piezoelectric substrate. With help of finite element method simulations, we calculate energy due to electromechanical conversion into bulk surface acoustic waves. This sets an upper limit resonator internal quality factor $Q_i$. To validate simulation, fabricate quarter wavelength coplanar waveguide GaAs measure $Q_i$ as function frequency, power temperature. observe linear increase...

Microscopic two-level system (TLS) defects at dielectric surfaces and interfaces are among the dominant sources of loss in superconducting quantum circuits, their properties have been extensively probed using resonators qubits. We report on spectroscopy TLSs coupling to strain field a surface acoustic wave (SAW) resonator. The narrow free spectral range resonator allows for two-tone where strong pump is applied one resonance while weak signal used probe different mode. map hole burnt by tone...

We introduce a simplified fabrication technique for Josephson junctions and demonstrate superconducting Xmon qubits with T1 relaxation times averaging above 50 μs (Q>1.5×106). Current shadow-evaporation techniques aluminum-based require separate lithography step to deposit patch that makes galvanic, connection between the junction electrodes circuit wiring layer. The eliminates parasitic junctions, which otherwise contribute significantly dielectric loss. In our patch-integrated...

Collective phenomena arise from interactions within complex systems, leading to behaviors absent in individual components. Observing quantum collective with macroscopic mechanical oscillators has been impeded by the stringent requirement that be identical. We demonstrate regime for motion of N = 6 oscillators, a hexamer, superconducting circuit optomechanical platform. By increasing couplings, system transitions motion, characterized <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"...

Abstract We demonstrate an on-demand source of microwave single photons with 71–99% intrinsic quantum efficiency. The is narrowband (300 kHz) and tuneable over a 600 MHz range around 5.2 GHz. Such device important element in numerous technologies applications. consists superconducting transmon qubit coupled to the open end transmission line. A π -pulse excites qubit, which subsequently rapidly emits photon into cancellation pulse then suppresses reflected by 33.5 dB, resulting 0.005 leaking...

The vacuum (i.e., the ground state) of a system in ultrastrong light-matter coupling contains particles that cannot be emitted without any dynamical perturbation and is thus called virtual. We propose protocol for inducing observing real mechanical excitations mirror enabled by virtual photons state tripartite system, where resonant optical cavity ultrastrongly coupled to two-level (qubit) and, at same time, optomechanically resonator. Real phonons are coherently when frequency modulated...

In this work, we demonstrate the excitation of surface acoustic waves (SAW) harmonics up to GHz regime in photolitographed devices fabricated on gallium arsenide (GaAs) by acting IDT metallization ratio among finger width and pitch. Specifically, observed 13th harmonic, which corresponds a frequency about 1.7 GHz. Moreover, employed time-resolved spectroscopy for isolating shape SAW bandpass-filter response (for each harmonic) eliminating interference between electromagnetic waves. Notably,...

Tailoring the decay rate of structured quantum emitters into their environment opens new avenues for nonlinear optics, collective phenomena, and communications. Here, we demonstrate a novel coupling scheme between an artificial molecule comprising two identical, strongly coupled transmon qubits microwave waveguides. In our scheme, is engineered so that transitions states same (opposite) symmetry, with respect to permutation operator, are predominantly one (the other) waveguide. The...

Superconducting qubits are one of the most advanced candidates to realize scalable and fault-tolerant quantum computing. Despite recent significant advancements in qubit lifetimes, origin loss mechanism for state-of-the-art is still subject investigation. Moreover, successful implementation error correction requires negligible correlated errors among qubits. Here, we ultra-coherent superconducting transmon based on niobium capacitor electrodes, with lifetimes exceeding 0.4 ms. By employing a...

Superconducting microwave metamaterials offer enormous potential for quantum optics and information science, enabling the development of advanced technologies sensing amplification. In context circuit electrodynamics, such can be implemented as coupled cavity arrays (CCAs). continuous effort to miniaturize devices increasing scalability, minimizing footprint CCAs while preserving low disorder becomes paramount. this work, we present a compact CCA architecture leveraging superconducting NbN...

Landau-Zener-St\"uckelberg-Majorana (LZSM) interference emerges when the parameters of a $\textit{qubit}$ are periodically modulated across an avoided level crossing. Here, we investigate occurrence LZSM phenomenon in nonlinear multilevel bosonic systems, where pattern is determined by multiple energy levels and cannot be described crossing between only two states. We fabricate superconducting resonators made flux-tunable Josephson junction arrays. The first device very weakly (the...

Collective phenomena in physics emerge from interactions among numerous components a complex system, leading to behaviors distinct those of individual parts. This domain includes classical like synchronization and extends quantum such as Bose-Einstein condensation super-radiance. Studying these controlled artificial systems allows for simulating natural systems. Solid-state mechanical oscillators, controllable via optomechanical coupling, have been proposed exploring collective phenomena,...

Quantum metrology, a cornerstone of quantum technologies, exploits entanglement and superposition to achieve higher precision than classical protocols in parameter estimation tasks. When combined with critical phenomena such as phase transitions, the divergence fluctuations is predicted enhance performance sensors. Here, we implement sensor using superconducting parametric (i.e., two-photon driven) Kerr resonator. The sensor, linear resonator terminated by supercondicting interference...