Efficient Quantum Algorithms for GHZ and W States, and Implementation on the IBM Quantum Computer

Efficient deterministic algorithms are proposed with logarithmic step complexities for the generation of entangled GHZN and WN states useful for quantum networks, and an implementation on the IBM quantum computer up to N=16 is demonstrated. Improved quality is then investigated using full quantum tomography for low‐N GHZ and W states. This is completed by parity oscillations and histogram distance for large‐N GHZ and W states, respectively. Robust states are built with about twice the number of quantum bits which were previously achieved. Entangled GHZN and WN quantum states can be efficiently and deterministically generated on the IBM quantum computer with 16 qbits up to N=16. The proposed scheme features logarithmic step complexities. Resulting improved quality is then characterized using full quantum tomography for low‐ N, while parity oscillations and histogram distance are used for large N values.