IIT Bombay breakthrough uses light to tune quantum states in ultra-thin materials

Mumbai, Dec 15 (PTI) Researchers from IIT Bombay have developed a simple light-based technique to create, control, and detect tiny quantum states in atom-thin materials, which could speed up the development of ultra-fast, low-power quantum and next-generation electronic devices.

Researchers at IIT Bombay have found a simple optical method to control quantum states in ultra-thin materials using linearly polarised light, a breakthrough that could eventually enable computers and electronic devices that are far faster and more energy-efficient than today's technology.

The materials studied are just one atom thick - far thinner than a human hair - and are known as two-dimensional (2D) semiconductors.

Inside these materials, electrons can sit in one of two distinct quantum states, called valleys.

However, to reliably control which valley electrons occupy - and to switch between them quickly and on demand - has been a major challenge.

"Previous methods required complicated experimental setups with carefully tuned circularly polarised lasers and often multiple laser pulses, and they only worked under specific conditions," said IIT Bombay Prof Gopal Dixit.

The findings reveal a new method that removes the need for complicated laser schemes by using just one linearly polarised pulse.

Researchers found that a subtle asymmetry in the laser's skewed polarisation waveform, introduced as a controlled delay between its polarisation components, is enough to push electrons into either valley.

By inverting the temporal skew, the induced valley polarisation can be switched between the two states, making the process fully reversible.

Dixit said the same pulse that switches the valley state also creates a tiny electric current, which acts as a built-in signal telling researchers which state was chosen.

This means the system can be controlled and read out at the same time - no second laser or additional instrument is needed, he added.

By reducing valley control to a single, easy-to-generate laser pulse, this finding simplifies experimental requirements while unlocking ultrafast, low-power quantum-state control.

It represents a major step toward future devices that use light to control information in 2D materials, potentially transforming technologies in both classical computing and quantum computing. PTI SM NSK