QRAM

Theory

The address and output registers of QRAM are composed of qubits instead of bits, though the memory array can be either quantum or classical.

Address register $a$: superposition $\sum _{i}\alpha _{i}|i\rangle _{a}$.

Data register $d$ with $D_{i}$ being the content of $i$th memory cell. QRAM is the operation $\sum _{i}\alpha _{i}|i\rangle _{a}\to \sum _{i}\alpha _{i}|i\rangle _{a}|D_{i}\rangle _{d}$.

References

https://arxiv.org/pdf/0708.1879.pdf