We present a modular system for time-resolved two-dimensional luminescence lifetime imaging of planar optical chemical sensors. It is based on a fast, gateable charge-coupled device (CCD) camera without image intensifier and a pulsable light-emitting diode (LED) array as a light source. Software was developed for data acquisition with a maximum of parameter variability and for background suppression. This approach allows the operation of the system even under daylight. Optical sensors showing analyte-specific changes of their luminescence decay time were tested and used for sensing pO2, pCO2, pH, and temperature. The luminophores employed are either platinum(II)-porphyrins or ruthenium(II)-polypyridyl complexes, contained in polymer films, and can be efficiently excited by blue LEDs. The decay times of the sensor films vary from 70 μs for the Pt(II)-porphyrins to several 100 ns for the Ru(II) complexes. In a typical application, 7 mm-diameter spots of the respective optical sensor films were placed at the bottom of the wells of microtiterplates. Thus, every well represents a separate calibration chamber with an integrated sensor element. Both luminescence intensity-based and time-resolved images of the sensor spots were evaluated and compared. The combination of optical sensor technology with time-resolved imaging allows a determination of the distribution of chemical or physical parameters in heterogeneous systems and is therefore a powerful tool for screening and mapping applications.

We construct the finite-temperature dynamical phase diagram of the fully connected transversefield Ising model from the vantage point of two disparate concepts of dynamical criticality. An analytical derivation of the classical dynamics and exact diagonalization simulations are used to study the dynamics after a quantum quench in the system prepared in a thermal equilibrium state. The different dynamical phases characterized by the type of non-analyticities that emerge in an appropriately defined Loschmidt-echo return rate directly correspond to the dynamical phases determined by the spontaneous breaking of Z2 symmetry in the long-time steady state. The dynamical phase diagram is qualitatively different depending on whether the initial thermal state is ferromagnetic or paramagnetic. Whereas the former leads to a dynamical phase diagram that can be directly related to its equilibrium counterpart, the latter gives rise to a divergent dynamical critical temperature at vanishing final transverse-field strength.arXiv:1712.02175v3 [cond-mat.stat-mech]

The Loschmidt echo (LE) is a purely quantum-mechanical quantity whose determination for large quantum many-body systems requires an exceptionally precise knowledge of all eigenstates and eigenenergies. One might therefore be tempted to dismiss the applicability of any approximations to the underlying time evolution as hopeless. However, using the fully connected transverse-field Ising model (FC-TFIM) as an example, we show that this indeed is not the case, and that a simple semiclassical approximation to systems well described by mean-field theory (MFT) is in fact in good quantitative agreement with the exact quantum-mechanical calculation. Beyond the potential to capture the entire dynamical phase diagram of these models, the method presented here also allows for an intuitive geometric interpretation of the fidelity return rate at any temperature, thereby connecting the order parameter dynamics and the Loschmidt echo in a common framework. Videos of the post-quench dynamics provided in the supplemental material visualize this new point of view.Equilibrium phase transitions are remarkable phenomena that have been under thorough experimental and theoretical investigation for decades. Over time, a number of advanced techniques such as scaling theory [1-3] and the renormalization group method [4-9] have been developed for the determination of the universal properties close to a critical point. One might ask whether an indepth study of dynamical critical phenomena far from equilibrium is possible along the lines established in the equilibrium framework. With the advent of modern ultracold atom [10-13] and ion-trap [14-16] experiments, this originally purely academic question has become accessible in laboratories as well.Dynamical quantum phase transitions (DPTs) occur in the dynamics of a quantum system after quenching a set of control parameters {Γ} of its Hamiltonian:Recently, the study of DPTs has focused on two largely independent concepts [17]. The first one, , resembles equilibrium Landau theory: A system undergoes a dynamical phase transition if the long-time limit of the order parameter is finite for one set {Γ i , Γ f }, whereas it vanishes for different final parameters {Γ f }. Furthermore, DPT-I also entails criticality in the transient dynamics of the order parameter and two-point correlators before reaching the steady state, giving rise to effects such as dynamic scaling and aging, which have been investigated theoretically [30][31][32] and also observed experimentally [33].The second concept, DPT-II, generalizes the nonanalytic behavior of the free energy at a phase transition in the thermodynamic limit (TL) to the out-ofequilibrium case. To this end, the LE has been introduced as a dynamical analog of a free energy per particle [34]. DPT-II has been extensively studied both theoretically [34][35][36][37][38][39][40][41][42][43] and in experiments [44,45]. As we aim to calculate dynamical phase transitions at finite preparation temperatures, we define the distance covered in Hilbert space between the pr...

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