Researchers at the Karlsruhe Institute of Technology (KIT) have made a groundbreaking discovery in the field of quantum computing and communication. By precisely controlling tin vacancies in diamonds using microwaves, they have taken a significant step towards the development of high-performance quantum computers and secure quantum communication networks. This discovery could have far-reaching implications for data processing and transmission, potentially ushering in a new era of unprecedented speed and security. Quantum computing and quantum communication are rapidly emerging as the next frontiers in digital technology.
Utilizing the Special Characteristics of Diamonds
This breakthrough revolves around having the power to manipulate a specific type of defect within diamonds, called a tin-vacancy (SnV) center. These defects have characteristic optical and magnetic properties that render them ideal as qubits, which are the basic units of quantum computers and quantum communication systems.
Traditional bits can only be either a 0 or 1, but qubits can also take on any value between 0 and 1 at the same time, hence enabling data processing speeds which exponentially faster as well as more secure means of transmitting data. Now, doctoral researchers Ioannis Karapatzakis and Jeremias Resch from the Physikalisches Institut at KIT have succeeded in controlling the electron spins of this qubit system with microwaves as well.
Improving Qubit Stability and Coherence
A major barrier to the development of these qubit-based quantum technologies comes from a lack of stability and coherence in the qubits. To solve the problem, Karapatzakis and Resch used a method called dynamical decoupling that reduced interference and boosted the coherence times of the diamond SnV centers to as long as 10 milliseconds — an order-of-magnitude improvement over previous efforts.
This also includes the use of superconducting waveguides to help direct microwave radiation efficiently to defects without producing heat. This is critical, as these defects work at ultracold temperatures not far from absolute zero—temperatures that are below what you’d find in space, and anything higher than this would make the qubits too uncontrolled to be useful. Their work, published in Nature Communications, represents a major advance towards the development of practical quantum technologies based on diamond.
Connecting qubits to photons
For efficient quantum communication, however, the quantum states of qubits must be converted to photons and transmitted using photons — which convey information in optical communication networks. As Resch puts it, “To communicate between two users or (at some point) between two quantum computers, we have to encode the qubit quantum states inside photons.
This is an important step in the ultimate goal of this project, and in showing that the qubits could indeed be optically read out and have stable spectral properties. The researchers note that their work is the first step in controlling tin-vacancy centers to realize qubits and photons that can be integrated seamlessly, enabling multi-node quantum repeaters for secure and efficient quantum communication networks.
