Tiny “Light-Twisting” Lasers For Faster, More Secure Encryption Keys

Quantum on-chip device that powers future ultra-secure, high-speed digital communication by encoding more information into single particles of light.
Problem:
Quantum key distribution (QKD) is a new way to create secure communication systems; however, it is limited to sending only a small amount of information at a time. Most current systems use qubits, which can carry at most one bit of information per photon, limiting overall speed. These qubits are also easily disrupted by noise, signal loss, and hardware imperfections, making real-world deployment difficult. Qudits are a potential solution, but while they could improve capacity and noise resistance, many existing designs require bulky optical components that are fragile and hard to align, making them more complex and resource heavy.
Solution:
The inventors developed an integrated micro laser to generate and manipulate high-dimensional quantum states. This device carries more information per photon and resists noise using 4D quits. The transmitter fits on a tiny semiconductor chip, replacing bulky, fragile optical parts. Its design keeps signals aligned in transmission, enabling quick switching between states and power levels for stronger security.
Technology:
The inventors fabricated a micro laser that generates direct, compact, and energy-efficient quantum states. To make this practical for real systems, they integrated the light source onto a III/V semiconductor chip (InGaAsP/InP). The device is made of two microring resonators linked by four spiral-shaped waveguides, with patterned gratings that shape the laser’s output. By using a coupling design, the chip can be reconfigured on demand to produce different high-dimensional quantum states. The laser’s output combines polarization and orbital angular momentum in a single beam, allowing the transmitter to create stable 4D signals directly from the chip without bulky external modulators.
Advantages:

Allows up to log2N higher information density than current solutions
Provides superior noise tolerance compared to existing solutions that are capped at one bit per photon
Tiny chip-based device, replacing current bulky tabletop optic systems
Consumes less energy, avoids expensive scaling complexity
Equipped with protection against common hacking methods via spatially indistinguishable qudit states
Maintains stable performance for at least two hundred minutes without needing constant realignment or recalibration

Stage of Development:

Bench Prototype

Schematic of Proposed High-Dimensional Quantum Key Distribution System - (a) System overview: a compact transmitter sending four-level (4D) quantum light signals through a communication channel, later separated by a mode sorter and detected via a single-photon avalanche diode (SPAD) (b) Schematic of micro laser design (c) Key sharing process of a the 4D BB84 protocol between sender and receiver (d) Scanning electron microscope photos of a fabricated device.
Intellectual Property: