Storing the information of 3 qubits in 2 qutrits with a generated clean ancilla.
Many quantum algorithms make use of ancilla, additional qubits used to store temporary information during computation, to reduce the total execution time. Quantum computers will be resource-constrained for years to come so reducing ancilla requirements is crucial. In this work, we give a method to generate ancilia out of idle qubits by placing some in higher-value states, called qudits. We show how to take a circuit with many O(n) ancilla and design an ancilla-free circuit with the same asymptotic depth. Using this, we give a circuit construction for an in-place adder and a constant adder both with O(log n) depth using temporary qudits and no ancilla. doi: 10.1109/ISMVL49045.2020.9345604
Jonathan M. Baker, Casey Duckering, Frederic T Chong
