Students from Alperton Community School, in collaboration with Orbyts Fellows Ralph Jason C. and Eleanor Kneip from UCL Physics and Astronomy, have explored more efficient ways to create Bell states on quantum computers. Quantum computers utilise qubits, which, unlike classical bits that are either 0 or 1, can exist in a quantum superposition of both 0 and 1 simultaneously. This unique property, along with entanglement, allows quantum computers to solve problems much faster than classical computers.

Entanglement is a special correlation between qubits where they cannot be described independently from each other, even when physically separated. This phenomenon is what enables quantum computers to outperform classical ones in various problems, such as the CHSH game, where a quantum algorithm can achieve an 85% success rate compared to a classical algorithm's 75%. Creating Bell states, which represent maximally entangled qubits, is crucial for important applications like quantum teleportation.

The research focused on optimising the creation of Bell states between physically distant qubits on IBM quantum computers. The standard IBM algorithm often employs numerous swap gates, which in turn use many controlled-NOT (CNOT) gates, leading to a higher chance of errors and inefficiency. To address this, the students devised three new algorithms aimed at reducing the number of CNOT gates and the overall circuit depth.

Comparing these algorithms, the students found one algorithm was the most effective, due to its low CNOT count and circuit depth, as well as its relative simplicity. While they also attempted to compare run times, the precision of only 1 microsecond was insufficient to differentiate the circuits on a small scale. This innovative work contributes significantly to improving the efficiency and reliability of quantum computations involving entangled states!