Quantum entanglement at the nanoscale

A significant step forward in the field of nonlinear optics.

Follow us onFollow Tech Explorist on Google News

In quantum entanglement, pairs of photons become connected so that if the state of one photon changes, the other changes instantly, no matter how far apart they are. Albert Einstein called this “spooky action at a distance.”

Today, entanglement is used to create the basic unit of quantum information, the qubit.

Usually, making pairs of photons requires large crystals. However, researchers at Columbia Engineering have found a new way to create these photon pairs more efficiently using smaller devices and less energy.

This is a big step forward in nonlinear optics, which involves changing the properties of light for use in things like lasers, telecommunications, and lab equipment.

P. James Schuck, a professor at Columbia Engineering, said this work connects large-scale and small-scale quantum optics. It lays the groundwork for highly efficient, scalable on-chip devices like tunable microscopic photon-pair generators.

The new device is only 3.4 micrometers thick to fit onto a silicon chip. This would make quantum devices much more energy-efficient and technically advanced.

To make the device, researchers used thin crystals of molybdenum disulfide. They stacked six of these crystals, rotating each layer by 180 degrees. As light passes through this stack, quasi-phase-matching changes the light, creating paired photons.

This is the first time quasi-phase-matching has been used in van der Waals materials to generate photon pairs at wavelengths that are useful for telecommunications. This new method is more efficient and less prone to error than previous techniques.

Professor P. James Schuck believes this breakthrough will make van der Waals materials the key to next-generation quantum technologies. These innovations will impact areas like satellite communication and mobile phone quantum communication.

Built on previous work

Schuck and his team improved their new device based on previous work. In 2022, they showed that materials like molybdenum disulfide are suitable for nonlinear optics, but the performance was limited because light waves interfered with each other in this material.

They used periodic poling to fix this, which helps with phase matching. By alternating the direction of the slabs in the stack, they could better control the light, allowing for efficient photon pair generation on a tiny scale.

Schuck said, “Once we realized how great this material was, we knew we had to try periodic poling to generate photon pairs efficiently.”

Journal Reference:

  1. Chiara Trovatello, Carino Ferrante, Birui Yang, Josip Bajo, Benjamin Braun t al. Quasi-phase-matched up- and down-conversion in periodically poled layered semiconductors. Nat. Photon, 2025 DOI: 10.1038/s41566-024-01602-z
Up next

Qubits to qudits: A new device uses quantum principles to relay information securely

Using quantum mechanics to transmit information more securely

The gemstone spinel can store quantum information

This discovery highlights the incredible potential of materials like spinel.
Recommended Books
Picks for you