title: Introduction to Quantum Technology
Creators: name: Saalbach, Klaus
Publisher: name: Universität Osnabrück
Year: 2025
Subjects: subject: Quantum technology
subject: Quantum computer
subject: Quantum sensing
subject: Cryptography
subject: 600 - Technik
subject: 355 - Militär
subject: 004 - Informatik
subject: 320 - Politik

description: This working paper provides a brief introduction to quantum technology as an emerging technology in the military and security area. Quantum technology is very promising for military and security-relevant applications; the major areas are quantum computing, quantum communication, quantum sensing, cryptoanalysis and quantum imaging. The four key concepts are quantum bits, superposition, entanglement and decoherence. The basic element is the quantum bit (qubit) where small particles are utilized for more variability, e.g., the spin of electrons, which can be used for faster calculations. Superposition means that quantum systems exist in two or more states simultaneously, i.e., like a spinning coin that could still land on either of both sides. But these systems are very sensitive and an interaction with the environment can result in loss of superposition, the decoherence. Therefore, quantum computers may need extreme cooling, special materials, good isolation from environment etc. which makes them difficult to handle. Currently, quantum computers have reached the Noisy Intermediate-Scale Quantum era with 50 to 100 qubits. For 2033, a computer with 2,000 logical qubits is planned. Entanglement is an intrinsic linkage between two or more quantum objects that works like an invisible band. If the quantum state of one entangled particle is changed, the state of the other particle changes immediately as well, which allows to transfer quantum information over large distances if one particle is in the sender and the other in the receiver. The sensitivity of quantum states makes it impossible to intercept an information exchange without altering the information, resulting in secure communication. A practical application is the Quantum Key Distribution QKD where a secure quantum key with entangled photons is used to protect messages that are sent over normal networks. China has launched two satellites in 2016 and 2022 for QKD and has a large QKD network on the ground as well. In 2024, Germany launched the microsatellite QUBE for QKD. In the area of quantum sensing, the US military develops quantum navigation chips which allow extremely sensitive and superior measurements for acceleration and angular velocity. Quantum sensors may improve the detection of submarines which is relevant for nuclear deterrence. In cryptoanalysis, the Shor algorithm allows factorization of large numbers into primes which may crack the important Rivest–Shamir–Adleman (RSA) encryption, but for the decryption of the secure RSA-2048 standard, larger quantum computers will be needed which will not be achieved before the 2030ies. In summary, some applications are mature while others are still theoretical. The development of quantum computers is still challenging. The quantum key distribution QKD is currently the most advanced application of quantum communication. Quantum sensors are currently developed as alternative to the Global Positioning System GPS while the quantum-based crack of current encryption methods may be achieved in the 2030ies. Further progress can be expected with a broader use of quantum technology.