Passive filters.
Measurable gains.
HERD is a patented infrared-blocking filter for superconducting quantum processors. It removes high-energy radiation that breaks Cooper pairs while leaving your microwave signals essentially untouched, improving qubit coherence and readout without redesigning your stack.
Break the IR trade-off
HERD filters provide more than 60 dB attenuation above typical Cooper-pair breaking frequencies while keeping in-band insertion loss below a few tenths of a decibel. You no longer have to choose between low-insertion loss and high-frequency absorption.
Protect coherence and readout
By draining high-energy radiation before it reaches the qubit chip, HERD reduces quasiparticle-inducing noise that limits coherence. Experiments using HERD-2 report sub-Hz quasiparticle tunneling rates, state-of-the-art coherence and QND readout fidelities around 99.93% in superconducting circuits.
Built for cryostats
HERD-2 is a compact, non-magnetic, SMA inline component designed for high-density cryostats. Performance is validated up to 145 GHz and has exceptionally low unit-to-unit performance variation and reliable cool-down behavior.
Research
Validation from the field
HERD filters are used in state-of-the-art experiments on superconducting qubits, including work on quasiparticle tunneling, coherence and high-fidelity readout.
Raising the Cavity Frequency in cQED
Demonstrates raising cavity frequency to 21 GHz while maintaining a standard 5 GHz transmon qubit. Achieves 8% quantum efficiency readout, qubit quality factor exceeding 10⁷, and coherence times reproducibly exceeding 100 μs.
A transmon qubit realized by exploiting the superconductor-insulator transition
Demonstrates a transmon-type qubit made from an NbN thin film weak link created by tuning near the superconductor–insulator transition. The junction-less design avoids oxide barriers and parasitic capacitance, showing feasibility of planar, high-gap superconducting qubits.
Co-designed reflective and leaky-waveguide low-pass filter for superconducting circuits
Presents a stepped-impedance low-pass filter with integrated hollow waveguide absorbers. Achieves 3 dB cutoff at 13.5 GHz, insertion loss below 0.45 dB under 8 GHz, and more than 52.7 dB rejection above 17.3 GHz.
Recovery dynamics of a gap-engineered transmon after a quasiparticle burst
Gap-engineered transmons show reduced sensitivity to quasiparticle bursts. Burst rates drop by a factor of a few, but elevated substrate temperature during radiation impacts lets quasiparticles overcome the engineered gap. Relaxation recovers in ~0.7 ms, while chip heating persists for several milliseconds, revealing limits of gap engineering without improved phonon evacuation.
Lumped-element broadband SNAIL parametric amplifier with on-chip pump filter for multiplexed readout
Describes a broadband SNAIL amplifier with integrated matching network and on-chip pump filtering, enabling wideband multiplexed qubit readout with improved isolation.
2D transmons with lifetimes and coherence times exceeding 1 millisecond
Tantalum transmons on high-resistivity silicon achieve 2D qubit lifetimes up to ~1.7 ms and echo coherence exceeding T₁, while supporting 99.994% single-qubit gate fidelity on a wafer-scalable platform.