A full list of previous publications is available here.
The High-Energy Radiation Drain (HERD) filter is an ultra-low-loss filtering technique that uses leaky waveguides to absorb high-frequency radiation harmful to superconducting qubits. In this work, we extend the concept by leveraging the parasitic impedance of the leaky-waveguide structure and integrating it into a stepped-impedance low-pass filter. The result is a compact HERD filter with sharp roll-off and strong suppression of unwanted high-frequency signals.
Thermal fluctuations constrain the precision of non-equilibrium devices, particularly at quantum scales where reducing uncertainty requires entropy dissipation. Clocks exemplify this trade-off, typically showing a linear relation between precision and dissipation. We theoretically identify a quantum many-body system where clock precision scales exponentially with entropy dissipation, surpassing known bounds. This finding shows that coherent quantum dynamics can break conventional limits, enabling ultra-precise, low-dissipation quantum technologies.
Entanglement is key to quantum networks. We demonstrate a method to generate entangled microwave photons via a driven superconducting circuit. Our method enables time- and frequency-matched entanglement of sideband modes in the resonance fluorescence spectrum. These orthogonal modes can be stored in separate quantum memories, enabling high-rate entanglement distribution across platforms, with applications in waveguide QED, distributed quantum computing, and quantum communication networks.
Atom-photon bound states emerge when an atom couples to a metamaterial, offering a platform for long-range interactions crucial to quantum technologies. This work experimentally investigates their formation and radiative nature by analyzing the emitted light, revealing the underlying energy structure. The approach introduces a powerful new method to probe internal dynamics of bound states, demonstrated here for the first time, and extends beyond the insights of previous studies.
What if superconducting electronics had the flexibility of transistors? We explore gate control of critical current in an Al/InAs nanowire embedded in a λ/4 resonator. Changes in resonant frequency and quality factor align with an effective temperature in the Mattis-Bardeen model. We also measure gate-response times of tens of nanoseconds, highlighting the system’s potential for cryoelectronic applications like switches and fast superconducting electronics.
Classical thermal machines are ubiquitous in the real world, but their quantum counterpart had so far been theoretical curiosities. Here, we build a quantum refrigerator that demonstrates for the first time an important real-world application—resetting of a qubit. Our quantum refrigerator—constituting of two superconducting qubits, each connected to a physical heat bath—autonomously cools down a target superconducting qubit to its ground state more effectively than conventional methods.
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Scalable quantum computing requires reliable communication between distant processors. Propagating microwave photons offer a solution, but photon loss limits transfer fidelity. We demonstrate frequency-bin encoded microwave photons by encoding a qubit state into two distinct frequency modes with high fidelity. This enables photon loss detection via heralding and supports error-detectable links. Our simple, hardware-efficient architecture is a versatile building block for superconducting and waveguide-based quantum networks.
We demonstrate a quantum thermal machine that uses dephasing noise as a resource for refrigeration. The setup features a superconducting artificial molecule coupled to two microwave waveguides acting as thermal reservoirs, with a third channel introducing tunable dephasing noise. By adjusting noise and temperature gradients, the system functions as a quantum refrigerator, engine, or accelerator. Measuring heat currents below 10⁻¹⁸ watts, this platform enables exploration of quantum thermodynamics in engineered thermal environments.
This paper presents a measurement scheme corresponding to homo-and heterodyne detection for stationary quantum states of light. These types of measurements are cornerstones in quantum optics and commonplace on propagating fields, but our method enables high-efficiency measurements also on confined cavity fields. Inspired by the “repeated interactions” model, which is normally used for calculations of open system dynamics, we show that a simple realization of the model can emulate both homo- and heterodyne measurements statistics. This has applications in quantum computing, for instance, in verification of quantum speedup for boson sampling that could be implemented with current and near-term technology.
Distributed quantum computing relies on quantum channels linking distant processors, requiring reliable photon generation from stationary qubits. We demonstrate a superconducting circuit that transfers a qubit state into a traveling microwave photon with 94.5% fidelity. Using a time-varying parametric drive, we shape the photon’s temporal profile for efficient, phase-stable absorption. This high-fidelity method enables robust state transfer and remote entanglement, advancing scalable distributed quantum computing.
The achieved goal of our work is to gain complete control of the symmetries available in a simple (artificial) diatomic molecule interacting with photonic mode continuum hosted in waveguides; using a remarkably simple yet unique device architecture. We show the versatile scope of this capability in two distinct experiments which also inspire various other interesting experiments and applications with this architecture. We believe these features are of intrinsic interest to the wide community of waveguide quantum electrodynamics, that transcends several experimental platforms, and is an increasingly popular platform for exploring light-matter interactions and, recently, facilitating quantum technologies.