Breakthrough in Quantum Computing: IISc Team Uses Single Photons to Realize Universal Quantum Gates and Six-Qubit Entangled States

In a significant advance towards practical quantum computing, researchers at the Indian Institute of Science (IISc) have successfully demonstrated the construction of universal quantum gates and the generation of a six-qubit entangled state using a novel photonic quantum walk technique. Unlike classical computers that rely on bits as ON or OFF states, quantum computers harness qubits, which can exist in superposition and entanglement, enabling superior computational power.

The IISc team, led by CM Chandrashekar, utilized the intrinsic polarization states of single photons to encode one qubit and employed a path encoding method to create two additional qubits per photon by splitting and recombining photon paths. This enabled a single photon to represent a three-qubit system. By entangling two such photons, they created a six-qubit system, a major leap in scalability for photonic quantum computing.

Using carefully tuned linear optical components like beam splitters, waveplates, and mirrors, the researchers orchestrated controlled quantum walks to implement universal quantum gates deterministically. This breakthrough overcomes previous limitations in photon-based quantum computing, such as noise sensitivity and operational inefficiency, making photonic qubits promising candidates for scalable and stable quantum computers operable at room temperature.

This research opens new avenues for constructing quantum computers that may one day achieve widespread use akin to classical computers, marking a crucial step forward in quantum technology.

Reference: IISc, Experimental realization of universal quantum gates and a six-qubit entangled state using a photonic quantum walk, Physical Review Applied (2025)