Fast quantum circuit cutting with randomized measurements

Understand

We propose a new method to extend the size of a quantum computation beyond the number of physical qubits available on a single device.

• This is accomplished by randomly inserting measure-and-prepare channels to express the output state of a large circuit as a separable state across distinct devices.
• Our method employs randomized measurements, resulting in a sample overhead that is $\widetilde{O}(4^k / \varepsilon ^2)$, where $\varepsilon $ is the accuracy of the computation and $k$ the number of parallel wires that are "cut" to obtain smaller sub-circuits.
• We also show an information-theoretic lower bound of $\Omega(2^k / \varepsilon ^2)$ for any comparable procedure.