Sweden Quantum
Sweden Quantum develops HERD, a non-magnetic cryogenic filter that blocks infrared radiation above 70 GHz while passing qubit control and readout signals with under 0.15 dB insertion loss. The filter supports readout, charge, and flux lines in superconducting and spin qubit systems, with published deployments at institutions including Yale, Princeton, and Chalmers.
- Quantum Computing
- Hardware
Funding
Founders
Founder details are not available yet.
Product
Problem
Infrared radiation in cryostats breaks Cooper pairs in superconducting qubits and excites spin qubits, significantly shortening coherence times. Standard filtering solutions either fail to block high-frequency radiation effectively or introduce excessive insertion loss that degrades readout signal integrity.
Solution
HERD provides high-energy radiation drain filters that block infrared radiation while letting qubit control and readout signals pass with minimal loss. The filters achieve under 0.15 dB insertion loss in the passband and greater than 60 dB attenuation from 70 to 145 GHz, effectively draining Cooper-pair-breaking radiation before it reaches the quantum processor. A flat response with less than 0.1 dB ripple on charge lines preserves pulse shapes, while the design supports mA-level bias currents on flux lines with low dissipation. The filters are fully non-magnetic and cryo-compatible, making them safe to mount close to flux-sensitive superconducting qubits and magnetically sensitive spin qubits alike. Published experiments at Yale, Princeton, PTB, EPFL, and Chalmers using HERD filters report quasiparticle tunneling rates below 1 Hz.
Target Audience
Primary customers are research groups and quantum computing companies operating superconducting or spin qubit systems in dilution refrigerators, including institutions such as Yale, Princeton, PTB, EPFL, and Chalmers that require cryogenic infrared filtering for qubit coherence preservation.
Features
- Ultra-low insertion loss under 0.15 dB typical in the DC–13.5 GHz passband for readout lines, minimizing signal degradation between QPU and first amplifier
- Stopband attenuation exceeding 60 dB from 70 to 145 GHz, blocking Cooper-pair-breaking infrared radiation across the full relevant spectrum
- Flat in-band response with less than 0.1 dB ripple on charge lines, preserving pulse shapes without altering attenuation profiles
- mA-level bias current handling on flux lines with low dissipation, enabling high bias currents while conserving cooling power
- Fully non-magnetic construction with non-magnetic RF connectors (SMA, SMP, SMPM, SMPS) adding no stray flux noise near qubits
- Compact 62.96 mm × 9.53 mm inline format with 50 Ω design impedance, operating from 0 K to 320 K
- Return loss better than 20 dB typical across the passband, verified through room-temperature measurements up to 140 GHz