How much quantum information can we store and access from a single qubit?
It is possible to fully encode one bit in one qubit. However, a qubit can hold more information, e.g. up to two bits using superdense coding. For a system of n components, a complete description of its state in classical physics requires only n bits, whereas in quantum physics it requires 2n−1 complex numbers.
How can machine learning be used to measure quantum devices?
Our contribution goes beyond the use of machine learning for data search and analysis, and instead demonstrates the use of algorithms to automate measurements. This works lays the foundation for learning-based automated measurement of quantum devices. Semiconductor quantum devices hold great promise for scalable quantum computation.
Why do we need so many quantum devices?
Scalable quantum technologies such as quantum computers will require very large numbers of quantum devices to be characterised and tuned. As the number of devices on chip increases, this task becomes ever more time-consuming, and will be intractable on a large scale without efficient automation.
How are quantum dot measurements performed in real time?
We present measurements on a quantum dot device performed by a machine learning algorithm in real time. The algorithm selects the most informative measurements to perform next by combining information theory with a probabilistic deep-generative model that can generate full-resolution reconstructions from scattered partial measurements.
How is the conductance of a quantum device measured?
Characterising such devices, which requires measurements of current or conductance at different applied biases and gate voltages, can be very time consuming. It is normally carried out following simple scripts such as grid scans, which are sequential measurements taken from a 2D grid for a pair of voltages.