We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.

The zero-point energy stored in the modes of an electromagnetic cavity has experimentally detectable effects, giving rise to an attractive interaction between the opposite walls, the static Casimir effect. A dynamical version of this effect was predicted to occur when the vacuum energy is changed either by moving the walls of the cavity or by changing the index of refraction, resulting in the conversion of vacuum fluctuations into real photons. Here, we demonstrate the dynamical Casimir effect using a Josephson metamaterial embedded in a microwave cavity at 5.4 GHz. We modulate the effective length of the cavity by flux-biasing the metamaterial based on superconducting quantum interference devices (SQUIDs), which results in variation of a few percentage points in the speed of light. We extract the full 4 × 4 covariance matrix of the emitted microwave radiation, demonstrating that photons at frequencies symmetrical with respect to half of the modulation frequency are generated in pairs. At large detunings of the cavity from half of the modulation frequency, we find power spectra that clearly show the theoretically predicted hallmark of the Casimir effect: a bimodal, "sparrow-tail" structure. The observed substantial photon flux cannot be assigned to parametric amplification of thermal fluctuations; its creation is a direct consequence of the noncommutativity structure of quantum field theory.Josephson junction | nanoelectronics | quantum mechanics A fundamental theoretical result of modern quantum field theory is that the quantum vacuum is unstable (1-6) under certain external perturbations that otherwise produce no consequences in a classical treatment (7). As a result of this instability, virtual fluctuations populating the quantum vacuum are converted into real particles by the energy provided by the perturbation. For example, the application of intense electrical fields extracts electron-positron pairs from a vacuum (Schwinger effect), the bending of space-time in the intense gravitational field at event horizons is responsible for the evaporation of black holes (Hawking radiation), the acceleration of an observer in the Minkowski vacuum results in the detection of particles (Unruh effect), and sudden changes in the boundary conditions of electromagnetic field modes or in the speed of light (index of refraction) create photons [dynamical Casimir effect (DCE)] (8). The DCE is a particular case of parametric amplification of vacuum fluctuations (3, 4, 6). To date, preliminary evidence for the analog of Hawking radiation has been obtained (9), whereas in the case of the DCE, a very recent experiment has reported production of photons by the nonadiabatic change of a boundary condition (10). Many other theoretical estimations and proposals for observing this effect in a variety of physical systems exist in the literature (11)(12)(13)(14)(15)(16)(17)(18)(19)(20).In this paper, we demonstrate the DCE by modulating the background in which the field propagates (3). We periodically change the index of refraction (which...

Landau-Zener (LZ) tunneling can occur with a certain probability when crossing energy levels of a quantum two-level system are swept across the minimum energy separation. Here we present experimental evidence of quantum interference effects in solid-state LZ tunneling. We used a Cooper-pair box qubit where the LZ tunneling occurs at the charge degeneracy. By employing a weak nondemolition monitoring, we observe interference between consecutive LZ-tunneling events; we find that the average level occupancies depend on the dynamical phase. The system's unusually strong linear response is explained by interband relaxation. Our interferometer can be used as a high-resolution Mach-Zehnder-type detector for phase and charge.

Hybrid quantum systems with inherently distinct degrees of freedom play a key role in many physical phenomena. Famous examples include cavity quantum electrodynamics [1], trapped ions [2], or electrons and phonons in the solid state. Here, a strong coupling makes the constituents loose their individual character and form dressed states. Apart from fundamental significance, hybrid systems can be exploited for practical purpose, noteworthily in the emerging field of quantum information control. A promising direction is provided by the combination between long-lived atomic states [2,3] and the accessible electrical degrees of freedom in superconducting cavities and qubits [4,5]. Here we integrate circuit cavity quantum electrodynamics [6,7] with phonons. Besides coupling to a microwave cavity, our superconducting transmon qubit [10] interacts with a phonon mode in a micromechanical resonator, thus representing an atom coupled to two different cavities. We measure the phonon Stark shift, as well as the splitting of the qubit spectral line into motional sidebands, which feature transitions between the dressed electromechanical states. In the time domain, we observe coherent conversion of qubit excitation to phonons as sideband Rabi oscillations. This is a model system having potential for a quantum interface, which may allow for storage of quantum information in long-lived phonon states, coupling to optical photons, or for investigations of strongly coupled quantum systems near the classical limit.Superconducting quantum bits based on Josephson junctions [5] have offered an unparalleled testing ground for quantum mechanics in relatively large systems. At the same time, Josephson devices constitute a promising implementation for quantum information processing. Basic quantum algorithms have indeed been recently demonstrated with phase [9] and transmon [10][11][12] qubits. The latter operate in the circuit cavity quantum electrodynamics (QED) architechture, in which the qubits couple to an on-chip [6] or 3-dimensional microwave cavity resonator [9]. The circuit QED setup, which enables coupling of qubits and non-destructive measurements of quantum states, can be regarded as the most feasible platform for quantum information.The forthcoming challenges in circuit QED include the construction of an interface to the storage and retrieval of qubit states in a long-lived quantum memory, as well as quantum communication [14] between spatially separated superconducting qubits. Hybrid quantum systems are showing promise for these goals because in principle one can combine the specific assets of each ingredient. Merger of macroscopic qubits with spin ensembles is intriguing due to the long lifetime of the latter [15, 16], but with the drawback of a difficult access and small coupling at the level of a single atomic degree of freedom.Micromechanical resonators were brought to the quantum regime of their motion only very recently [17, 18]. They have been suggested as a plausible interfacing medium for Josephson junction qubits [...