Microfabrication of atomic and optical components plays an increasingly important role in the development of quantum technologies and their application in fields such as sensing, timing and spectroscopy. Driven forward by advances in micro-electromechanical systems (MEMS), new techniques are now used for critical atomic and optical components at the heart of quantum technologies, including diffractive optics, atomic vapour cells and miniaturised ion traps. A range of other miniaturised technologies, such as hollow-core waveguides and integrated photonics, also add to the capabilities of emerging quantum devices. These components offer the potential to scale atomic quantum devices down to chip-scale packages, increasing the application range and facilitating their in-field deployment. Additionally, miniaturisation may also unlock physical regimes, such as thin media effects and atom–interface interactions, opening avenues for new research which cannot be accessed using larger conventional components.

Quantum technologies (QTs) have matured over the past decade. A range of different technologies utilise atomic, photonic or large-mass optomechanical systems in quantum states. Quantum metrology experiments such as those using atomic clocks have been pushed to evermore precision, and superconducting devices have been used to implement quantum information processing, to name only some. What is common to all those QT implementations is that they in some regards outperform their classical counterparts or hold promise to do so. The development of QT systems is mostly driven by the desire to use them for applications such as new forms of computation, communication and sensing.

Technology is the product of understanding physical processes and learning how to control them in order to achieve desired objectives. To be practically usable, technology requires a degree of reliability, which can be achieved by robust system design and control [1].

The development of useful quantum technologies will heavily rely on assembling many sub-systems that exhibit quantum properties. These systems do not spontaneously assemble themselves into useable quantum machines: they rely on advanced fabrication techniques at micro- and nanometre scales. Examples of such techniques include the fabrication of electrodes and waveguides for trapped ions, of Josephson junctions and microwave chips for superconducting circuits, of electrodes for the control of quantum dots or the fabrication of low-disorder semi-conductors for the operation of Majorana Zero Modes.

Quantum computing advantage emerges not from brute force power, but from subtle differences in information processing that can occur for key bottleneck subroutines. In 2019, the Google Quantum AI team performed a landmark experiment demonstrating quantum computational supremacy (Arute et al., 2019) where they performed a quantum computation that, at the time, could not be done on a classical supercomputer. This was remarkable because it was achieved by a processor with only 53 qubits, an observation that emerged from theoretical work which identified that quantum computers could have a massive advantage for certain specially designed benchmarking tasks (Boixo et al., 2018; Bremner et al., 2016).

Quantum cryptography bases its security proofs on physical assumptions. A longstanding observation in the field is that we may be able to do more cryptographic tasks when we assume not only the laws of quantum mechanics but also the impossibility of superluminal signaling (i.e., that information cannot travel faster than the speed of light). Relativistic quantum cryptography takes into account the spatial locations of the parties involved and uses the impossibility of superluminal signaling as a basis for security. Previous efforts in this field have been fruitful, both theoretically and experimentally.

Quantum technologies, including computing, communication/security and sensing, have significantly advanced over the last years. Industry-specific applications are now being intensely researched and healthcare, medicine and the life sciences represent one of the focus areas.

Photonic quantum memories are required in many applications in quantum information science with varying performance requirements depending on specific applications. Although classical light storage has been demonstrated in time scales of minutes (Dudin et al., 2013; Heinze et al., 2013) to hours (Ma et al., 2021) in different systems, storing true single photons and single photon level coherent pulses are still limited to around a few seconds at most (Wang et al., 2021; Ortu et al., 2022; Hain et al., 2022; Stas et al., 2022). In this question, we would like to explore what the challenges for quantum memory storage for the purposes of quantum communication and the distribution of entanglement are, e.g. in quantum repeaters. Furthermore, recent work has proposed using quantum memories with hour-long storage times for quantum computation (Gouzien and Sangouard, 2021) and physically transporting single photons for astronomical interferometry (Bland-Hawthorn et al., 2021) and global quantum communications (Wittig et al., 2017; Gündoğan et al., 2023).

Quantum technologies (QTechs) have the potential to have revolutionary effects in scientific, technological and commercial areas in equal measure. This includes major transformations boosted by quantum computing, quantum communication and quantum sensing, with applications ranging from information technologies to chemistry or finance.