Quantum computers, by exploiting quantum phenomena such are superposition and entanglement, hold the promise for solving efficiently important computational problems that are nowadays intractable for even the most powerful supercomputers. One of the most famous, though not necessarily the most realistic example is the factorization of large numbers using Shor’s algorithm. It has been shown that a 2000-bit number could be decomposed in a bit more than one day using a quantum computer whereas a data center having a size of approx. 400.000 km2 and using today’s fastest supercomputer would require around 100 years. Up to now, quantum computing has been a field mostly dominated by physicists. They are working on the design and fabrication of the basic units of any quantum system, called quantum bits or qubits. They have focused primarily on the enhancement of gate fidelities and on the improvement of coherence properties of qubits. However, building a quantum computer involves more than producing ‘good’ qubits. It requires the development of a scalable quantum system architecture and then contributions from different fields such as formal languages, compilers, operating systems, routing and interconnects, electronics, and computer architecture. Therefore, a special issue on Quantum Computer Architecture is proposed to present an overview of recent research from all over the world that focuses on the scaling and computer architecture issues. A long term scientific goal is also to create a new community of quantum computer engineers which will collaborate on the joint challenges.@en