These Indian Professors Fixed a 16-Year-Old Quantum Algorithm With the Wrong Answer

A research group at TCG CREST (The Chatterjee Group Centres for Research and Education in Science and Technology) has found a way to make a key quantum algorithm run faster by doing something counterintuitive:  keeping the wrong answer. The work, led by Professor Srinivasa Prasannaa, improved the performance of the Harrow–Hassidim–Lloyd (HHL) algorithm, a foundational method for solving systems of linear equations on quantum computers. The approach, called Psi(ψ)HHL, reduces a major runtime bottleneck without adding extra quantum hardware or circuit depth. “At the end of the day, what you’re doing is solving problems,” Prof Prasannaa tells AIM. “A quantum algorithm is what tells you how to change those qubit strings towards solving a specific problem, just as a classical algorithm tells you how to change bit strings.” The breakthrough matters because HHL sits at the heart of many proposed quantum applications, from chemistry simulations to optimisation.&nbs