Quantum information science is entering a second phase, the Quantum Evolution 2.0, in which the challenge has shifted from demonstrating coherent control of individual quantum states to building scalable multi-qubit processors and networks. This transition places materials science at the center of the field. Across superconducting circuits, quantum defects, quantum photonic devices, and emerging materials platforms, including two-dimensional materials and heterostructures, performance is now limited less by device design than by poorly controlled surfaces, buried interfaces, and defects whose atomic identities remain incompletely known. This review surveys the materials challenges of these quantum platforms together with the characterization methods needed to resolve them. For each platform we identify the dominant decoherence mechanisms, the current state of materials understanding, and the most pressing open materials problems. A cross-platform comparison then reveals a shared structure-coherence problem. The implicated material chemistry recurs across platforms, involving light elements in disordered or buried environments, yet no platform can quantitatively connect a specific atomic-scale structure to a measured change in coherence. We close by identifying three needs, mechanistic understanding of decoherence at the atomistic level, high-throughput proxy metrics predictive of device performance, and characterization tools built for quantum materials, whose resolution would advance coherence, scalability, and integration across all platforms.
Quantum information science is entering a second phase, the Quantum Evolution 2.0, in which the challenge has shifted from demonstrating coherent control of individual quantum states to building scalable multi-qubit processors and networks. This transition places materials science at the center of the field. Across superconducting circuits, quantum defects, quantum photonic devices, and emerging materials platforms, including two-dimensional materials and heterostructures, performance is now limited less by device design than by poorly controlled surfaces, buried interfaces, and defects whose atomic identities remain incompletely known. This review surveys the materials challenges of these quantum platforms together with the characterization methods needed to resolve them. For each platform we identify the dominant decoherence mechanisms, the current state of materials understanding, and the most pressing open materials problems. A cross-platform comparison then reveals a shared structure-coherence problem. The implicated material chemistry recurs across platforms, involving light elements in disordered or buried environments, yet no platform can quantitatively connect a specific atomic-scale structure to a measured change in coherence. We close by identifying three needs, mechanistic understanding of decoherence at the atomistic level, high-throughput proxy metrics predictive of device performance, and characterization tools built for quantum materials, whose resolution would advance coherence, scalability, and integration across all platforms.
Quantum memories, which are devices that store and retrieve fragile quantum states on demand,are central to scalable quantum networks, distributed quantum computing, and advanced quan-tum sensing. The performance, reliability, and scalability of a quantum memory are set, to alarge degree, by the materials from which it is built. This review provides a comparative analy-sis of leading quantum memory platforms, namely superconducting circuits, semiconductor spinqubits, diamond color centers, quantum dots, topological semiconductor and superconductorhybrids, magnon systems, and rare-earth ions in solids, from a materials science point of view.We first set out a compact, materials-level theory that connects host properties to device coher-ence and to the quality of the photon and spin interface. For each platform we then examine theprimary material systems, their intrinsic quantum properties, the state of the art in synthesisand fabrication, and the role of material imperfections such as defects, impurities, and inter-faces in limiting coherence. We analyze material-dependent sensitivity to environmental noise,the challenges of integration with other quantum and classical components, and the emergingmaterials that may overcome present limits. Synthesizing across platforms, we identify recur-ring materials themes. These include the control of defects and interfaces, the need for highpurity and isotopic engineering, and the close coupling between a quantum system and its hostmatrix. We close with a forward view on how materials innovation, supported by computationaldiscovery and advanced characterization, can address the main bottlenecks and bring practicalquantum memories closer.
Two-dimensional (2D) materials have emerged as a versatile and powerful platform for quantum technologies, offering atomic-scale control, strong quantum confinement, and seamless integration into heterogeneous device architectures. Their reduced dimensionality enables unique quantum phenomena, including optically addressable spin defects, tunable single-photon emitters, low-dimensional magnetism, gate-controlled superconductivity, and correlated states in Moiré superlattices. This Roadmap provides a comprehensive overview of recent progress and future directions in exploiting 2D materials for quantum sensing, computation, communication, and simulation. We survey advances spanning spin defects and quantum sensing, quantum emitters and nonlinear photonics, computational theory and data-driven discovery of quantum defects, spintronic and magnonic devices, cavity-engineered quantum materials, superconducting and hybrid quantum circuits, quantum dots, Moiré quantum simulators, and quantum communication platforms. Across these themes, we identify common challenges in defect control, coherence preservation, interfacial engineering, and scalable integration, alongside emerging opportunities driven by machine−learning−assisted design and integrated experiment−theory feedback loops. By connecting microscopic quantum states to mesoscopic excitations and macroscopic device architectures, this Roadmap outlines a materials-centric framework for integrating coherent quantum functionalities and positions 2D materials as foundational building blocks for next-generation quantum technologies.
Superconducting and photonic qubits are the two promising platforms for quantum computation. This review investigates different materials that are being used to advance these platforms, detailing the structural, electrical, and thermal properties that influence qubit performance. The discussion on superconducting qubits covers material properties critical for achieving low-loss circuits, the impact of two-level system defects, and the engineering of Josephson junctions. In contrast, photonic qubits, which leverage light for quantum information processing, are examined through the lens of material platforms such as silicon-based photonics and III–V semiconductors. The chapter also highlights fabrication challenges, qubit coherence improvements, and recent advances in single-photon sources for scalable quantum systems. By analyzing the intersection of materials science, quantum mechanics, and device engineering, this review provides insights into the optimization of quantum hardware for future large-scale quantum computing applications.
For future quantum technologies and in particular for quantum architecture systems, one needs to consider scalability and reproducibility in order to be able to handle and add easily as many qubits of information as possible on a given platform. Quantum coherence and quantum information are fragile and thus requires the need for many qubits to be created, to interact and quantum information to be preserved. Currently there are either very good qubits in terms of fidelity but poor scalability or very good scalability but poor fidelity thus requiring more qubits to compensate. Most of the current platforms are in solid-state physics such as superconducting, dopants in silicon, quantum dots in III-V semiconductors or defects in diamond. The main interest for condensed matter systems is the fact that it is potentially scalable as integration is possible in the future, already demonstrated in the ‘classical’ semiconductor industry. Nevertheless, there are some true challenges in controlling and understanding the mechanisms of decoherence, losses and unwanted effects in these ‘dirty’ systems. As quantum technologies require ultimate control of quantum effects such as maintaining quantum coherence, quantum superposition and entanglement, it pushes towards deeper knowledge of underlying material and condensed matter physics. Photons are of particular interest as they are good carriers of quantum information and one aim is to explore a fully integrated photonic quantum circuit which would be a hybrid system made of stationary solid-state qubits (we will call them quantum emitters) coupled together via single photons travelling within a common optical bus that is photonics-ready for quantum communications within a network of quantum nodes. In this presentation, we will present our latest developments and results towards the integration of quantum emitters with photonic structures with nanosize features. In the first part, our platform is described which consists of glass and thus directly compatible with optical fibres. It is based on the technique of exchanged ions within the glass in order to create locally a particular confinement of the light. The next part will concern our latest results on two different quantum emitters. The first one is based on perovskite nanocristals that can be synthetised chemically and giving rise to quantum optics-type of emitters. The second one is based on the so-called silicon-vacancy defect centre in nanodiamonds. These emitters are produced by the high-pressure/high-temperature method and lead to promising results for quantum technologies. Finally, the last part will treat the nanophotonics approaches in order to couple efficiently these emitters with our platform.
With massive improvements in device coherence times and gate fidelity over the past two decades, superconducting quantum devices have emerged as a leading technology platform for next generation quantum computing. While many of these improvements have been driven through optimized device designs and geometries, the presence of defects, impurities, interfaces, and surfaces in the constituent materials continue to limit performance and present a critical barrier in achieving scalable quantum systems with long coherence times. As part of the Superconducting Quantum Materials and Systems (SQMS) center, we have applied state-of-the-art materials characterization techniques, such as scanning/transmission electron microscopy, secondary ion mass spectrometry, and atom probe tomography, to identify structural defects and chemical inhomogeneities in superconducting qubits. In this review, we discuss the findings of these efforts as they relate to the inherent surfaces, interfaces, impurities, and defects in superconducting qubits. Through this comprehensive investigation, we provide insight into possible sources of dissipation in these systems. Further, we supplement these findings with potential strategies for mitigating these undesired features in an effort to systematically and intelligently improve the coherence times of superconducting qubits.
While significant strides have been made to increase the coherence time of superconducting qubits, further advancements are essential for realizing scalable quantum computing. Decoherence is often a result of loss and noise stemming from two-level systems and excess quasiparticles, arising due to material defects, fabrication processes, and ambient exposure, particularly at surfaces and interfaces. Our recent efforts to mitigate these decoherence mechanisms have employed a variety of strategies, including low-loss surface encapsulation materials, advanced substrate preparation techniques, modifications to metal film growth, and the development of novel fabrication processes. The structural and chemical properties of materials, surfaces, and interfaces are studied using scanning probe microscopy, electron microscopy, photoelectron spectroscopy, mass spectrometry, and X-ray diffraction, which is correlated to device performance metrics, including superconducting resonator internal quality factor and qubit T1 time. This information is used to identify and understand material sources of loss and their origins in the device fabrication process. Through multi-institution efforts within SQMS we have identified the loss mechanism of interstitial hydrogen in niobium-based devices and shown how standard fabrication processes introduce these hydrides, developing strategies to mitigate their formation.1 Furthermore, we have characterized the metal-substrate interface, including the loss of niobium-silicides formed at that interface, and developed silicon surface treatments that reduce atomic scale roughness and oxygen content at the metal-substrate and Josephson junction interfaces.2-4 By developing the connection between materials properties and the overall performance of superconducting quantum circuitry, we can develop fabrication strategies to mitigate material losses, thus supporting the ongoing efforts to enhance coherence time in superconducting quantum devices. 1. Torres-Castanedo, C. G.*, Goronzy, D. P.*, et al., Adv. Funct. Mater., 2401365 (2024) 2. Lu, X., et al., Phys. Rev. Materials 6, 064402 (2022) 3. Berti, G., Appl. Phys. Lett. 122, 192605 (2023) 4. Kopas, C. J., Goronzy, D. P., et al., arXiv:2408.02863 (2024)