An Innovative Six-Qubit Photonic System from IISc Helps India Reach Quantum Milestone.
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India’s quantum quest reached a milestone when the Indian Institute of Science (IISc) developed a six-qubit photonic gadget. The design and implementation of universal quantum gates using single photon manipulation is the focus of this achievement.
The goal of the research is to make significant progress towards the ultimate goal of developing potent quantum computers that can eventually be used extensively, much like modern-day classical computers. The scientific announcement was released around November 1, 2025, and was included in the KERNEL features of the Indian Institute of Science’s Office of Communications (OoC).
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Unlocking the Power of Quantum Phenomena
Using quantum phenomena like superposition and entanglement, quantum computers outperform traditional computers in computing. Classical computers employ bits that can only be ON (1) or OFF (0), while quantum computers use qubits.
The notion of superposition permits a qubit to exist in both ON and OFF modes, giving it a quantum advantage. Additionally, entanglement is a potent linking mechanism that occurs when two or more particles are so closely related that, even when they are separated by great distances, an impact on one instantly affects the other. The key to enabling these systems to conduct calculations beyond the capabilities of conventional machines is qubits’ capacity to exist in several states simultaneously due to superposition.
The Architecture of the Six-Qubit Photonic System
C M Chandrashekar, a researcher at IISc’s Department of Electronic Systems Engineering and the Department of Instrumentation and Applied Physics, headed the team that created this discovery. Their study concentrated on encoding information as qubits by utilising the physical properties of photons, which are packets of light.
The scientists were able to modify individual photons to work as a set of three qubits in this particular arrangement. An intrinsic qubit is formed from the two polarisation states that each individual photon inherently has. The researchers used an advanced method called route encoding to encode more qubits. To do this, a single travelling photon is split into two distinct spatial routes while it is still in superposition. This is done twice, and the paths are then recombined. By doing this, the photon acquired three qubits in total: two from the route encoding approach and one from its polarisation states.
The researchers successfully demonstrated the creation of a six-qubit entangled state by using the same configuration to entangle the states of two such photons in order to obtain the desired six-qubit system.
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Constructing Universal Quantum Gates
Quantum computers need their own set of operations, known as quantum gates, which are similar to the logic gates used by classical computers, such as AND, OR, and NOT. These required quantum gates were built by the IISc team using their novel six-qubit technology.
A gradual succession of quantum walks a precise procedure in which a particle is permitted to move about under control were used to realise the building. It was necessary to use linear optical components, such as waveplates, beam splitters, and mirrors, in order to experimentally accomplish this process utilizing photons. The team achieved the full set of universal quantum gates needed for quantum computation by meticulously adjusting these elements.
Advantages and Future Outlook
The selection of photonic qubits is a key component of this accomplishment. Because photonic qubits can operate effectively at ambient temperature and are inherently robust against environmental noise, they are ideal for real-world quantum computing applications.
The discovery is important because it demonstrates experimentally how single photons may deterministically create multi-qubit gates and, crucially, encode multiple qubits. A significant breakthrough has been made with the deterministic realisation of these gates, which was not the case with previous photon-based methods.
Building on the fundamental research being carried out at institutes like IISc, which is described in publications like KERNEL, this demonstration offers a clear route forward towards the objective of developing publicly accessible quantum computers. This six-qubit system’s creation marks a significant turning point in India’s efforts to build quantum computing.
