Aalto University researchers are the first in the world to measure qubits with ultrasensitive thermal detectors—thus evading the Heisenberg uncertainty principle.

Chasing ever-higher qubit counts in near-term quantum computers constantly demands new feats of engineering.

Among the troublesome hurdles of this scaling-up race is refining how qubits are measured. Devices called parametric amplifiers are traditionally used to do these measurements. But as the name suggests, the device amplifies weak signals picked up from the qubits to conduct the readout, which causes unwanted noise and can lead to decoherence of the qubits if not protected by additional large components. More importantly, the bulky size of the amplification chain becomes technically challenging to work around as qubit counts increase in size-limited refrigerators.

Bolometer-Based Qubit Measurement

Cue the Aalto University research group Quantum Computing and Devices (QCD). They have a hefty track record of showing how thermal bolometers can be used as ultrasensitive detectors, and they just demonstrated in an April 10 Nature Electronics paper that bolometer measurements can be accurate enough for single-shot qubit readout.

Overcoming the Heisenberg Uncertainty Principle

To the chagrin of many physicists, the Heisenberg uncertainty principle determines that one cannot simultaneously know a signal’s position and momentum, or voltage and current, with SciTechDaily