Researchers at KIT Achieve Breakthrough in Diamond-Based Quantum Computing
For the first time in Germany, researchers from the Karlsruhe Institute of Technology (KIT) from Helmholtz Information have demonstrated precise control of tin-vacancy centers in diamonds using microwaves. These defects, which possess unique optical and magnetic properties, can be utilized as qubits—the fundamental units of quantum computers and quantum communication. This breakthrough represents a significant step forward in the development of powerful quantum computers and secure quantum communication networks. (Source: Karlsruhe Institute of Technology – Press Releases)
Quantum computers and quantum communication are considered groundbreaking technologies, promising much faster and more secure data processing and transmission compared to classical computers. At the core of quantum computers are qubits, the quantum mechanical counterparts to bits in traditional computing.
While classical digital communication typically involves transmitting information via laser pulses through fiber optics, quantum mechanics leverages individual photons, making data exchanges virtually immune to eavesdropping. Optically addressable qubits—those that can be controlled or read with light—are particularly suitable for storing and processing quantum information and for interfacing with photons in quantum systems.
The Challenge of Qubit Stability
One of the most critical challenges in quantum computing is extending the coherence time of qubits—the duration they can stably store information. The development of efficient and scalable quantum computers hinges on the ability to control and stabilize qubits effectively, ensuring their properties can be practically applied.
At the KIT’s Institute of Physics, doctoral students Ioannis Karapatzakis and Jeremias Resch have been investigating how to precisely control a specific diamond defect known as the tin-vacancy center (SnV). Their research is part of the “Quantenrepeater.Link (QR.X)” project for secure fiber-based quantum communication and the SPINNING project, which focuses on a spin-photon-based quantum computer built on a diamond platform—both funded by the German Federal Ministry of Education and Research.
“A defect in the lattice structure of carbon atoms in a diamond occurs when atoms are missing or replaced by others, such as tin,” explains Karapatzakis. These defects, with their special optical and magnetic properties, can be used as qubits for quantum communication. They allow for precise manipulation of their states, such as electron spin, via light or microwaves, making them stable qubits that can store, process information, and interface with photons.
Significant Improvement in Coherence Times
Diamond-based qubits offer the advantage of being in a solid form, making them easier to handle than other quantum materials like atoms in a vacuum. By using microwaves to control these qubits, Karapatzakis and Resch successfully influenced the electron spins of the tin-vacancy centers and made this process observable. “We significantly improved the coherence times of SnV centers in diamond, extending them up to ten milliseconds,” Resch reports. This improvement was achieved through dynamic decoupling, a method that minimizes disturbances. Additionally, the researchers were the first to demonstrate that these diamond defects can be efficiently controlled using superconducting waveguides, which direct microwaves to the defects without generating heat. “This is crucial because these defects are typically studied at very low temperatures, close to absolute zero. Any increase in temperature would render the qubits unusable,” Karapatzakis notes.
“To enable communication between two users—or in the future, between two quantum computers—it’s essential to transfer the quantum states of the qubits to photons,” Resch explains. “By optically reading the qubits and achieving stable spectral properties, we’ve taken an important step in this direction. Our results in controlling tin-vacancy centers in diamonds hold significant potential for advancing secure and efficient quantum communication.”
KIT/M. Lehné, 19.09.2024
Note: The article has been translated from German to English. It is based on a press release from KIT.
The original press release can be found at:
Quantenkommunikation: Effiziente Ansteuerung von Diamant-Qubits mit Mikrowellen (only in german)
The original publication can be found at (Open Access):
Ioannis Karapatzakis, Jeremias Resch, Marcel Schrodin, Philipp Fuchs, Michael Kieschnick, Julia Heupel, Luis Kussi, Christoph Sürgers, Cyril Popov, Jan Meijer, Christoph Becher, Wolfgang Wernsdorfer, David Hunger: Phys. Rev. X 14, 27 August 2024, DOI: 10.1103/PhysRevX.14.031036
Localization in the Helmholtz Information:
Helmholtz Information, Program 2: Natural, Artificial and Cognitive Information Processing, Topic 2: Quantum Computing
Contact:
Prof. Dr. David Hunger
Physikalisches Institut (PHI)
Karlsruhe Institute of Technology (KIT)
Phone: +49 721 608-43510
E-Mail: david.hunger@kit.edu
Prof. Dr. Wolfgang Wernsdorfer
Physikalisches Institut (PHI)
Karlsruhe Institute of Technology (KIT)
Phone: +49 721 608-43430
E-Mail: wolfgang.wernsdorfer@kit.edu
Ioannis Karapatzakis
Physikalisches Institut (PHI)
Karlsruhe Institute of Technology (KIT)
Phone: +49 721 608-43520
E-Mail: ioannis.karapatzakis@kit.edu
Jeremias Resch
Physikalisches Institut (PHI)
Karlsruhe Institute of Technology (KIT)
Phone: +49 721 608-43514
E-Mail: jeremias.resch@kit.edu
Contact for this press release:
Margarete Lehné
Pressesprecherin (interim)
Karlsruhe Institute of Technology (KIT)
Phone: +49 721-608-41105
E-Mail: presse@kit.edu
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The Research Field “Helmholtz Information” is one of the six research fields of the Helmholtz Association and serves as its digital innovation center. Here, advanced and future computer architectures merge with insights from materials research, data science, and life sciences. Inspired by nature, supported by brain research, and enriched by modern approaches in artificial intelligence, experts from the Forschungszentrum Jülich, Karlsruhe Institute of Technology, Helmholtz-Zentrum Hereon, and the Helmholtz-Zentrum Berlin are shaping the digital future in science, business, and everyday life.
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