Future quantum computers could open new scientific and engineering frontiers, impacting existential challenges like climate change. However, quantum information is delicate; it leaks with time and is prone to significant errors. These errors are exacerbated by imperfect reading and writing of quantum bits (qubits). These challenges fundamentally limit our ability to run quantum programs, and could hold back this powerful technology. Fast and accurate qubit readout, therefore, is essential for unlocking the quantum advantage. Current quantum computers use conventional cameras for reading qubits, which are inherently slow and noisy.
UW-Madison researchers use quanta (single-photon) sensors for fast and accurate qubit readout. Quanta sensors detect individual photons scattered from qubits, thus enabling sensing qubits at 2-3 orders of magnitude higher speeds (few microseconds from ~10 milliseconds), thereby transforming the capabilities (speed, accuracy) of future quantum computers, and for the first time, paving the way for scalable and practical quantum computing.