Letter from the Editors: The Past and Present of Fashion Cities

In the past decade or so, discussion has increasingly addressed the need to rip apart the idea of a single fashion history stemming from Europe and North America which opened up with the outsourcing of the postwar period (Ling, Lorusso, and Segre Reinach 2019). Research has presented an open perspective, engaging with fashion beyond the boundaries of the traditional fashion capitals, considering skills, specialisms and placemaking strategies, fostered in diverse locations across the globe (Breward and Gilbert 2006; Skov 2011; Brydges, Hracs, and Lavanga 2018). Fashion affects elites and non-elites; cities in core and periphery areas alike. Furthermore, the structure of the fashion industry has varied from historical period to historical period and between cities, regions, and nations (Breward and Gilbert 2006; Rantisi 2004). The industry is composed of complex transnational supply chains which encompass textile and clothing manufacturing, the organization of temporary clusters like trade shows and fashion weeks, and (digital) media management (Skov 2006; Rocamora 2017; Wubs and Maillet 2017; Blaszczyk and Wubs 2018; Lavanga 2018; Huang and Janssens 2019). While scholars across the globe have enriched the geography of fashion by studying locations beyond the “big four,” there remains a need for better understanding of fashion centers from global and evolutionary perspectives. Employing an interdisciplinary approach, combining business history, economic history, fashion studies and economic geography, this special issue aims to present a burgeoning perspective. It focuses on the spatial and transnational dimensions of the industry, taking a long-term historical perspective—from Paris in the late nineteenth century to Turin and London in the early-mid twentieth century—while also providing provocations addressing how we could define and study fashion cities. As business historians and economic geographers, we are cautious to predict the future, but clearly, the rise of China as an economic superpower may create a cultural shift that could affect the power structure of the fashion industry. China is no longer the global sweatshop. It has become the largest consumer market of the world with a significant interest in fashion and luxury, complemented by an increasing number of domestic fashion designers and brands (Ling and Segre Reinach 2018). Chinese brands excel in their domestic market but often have not expanded fully in the West, likely as it is not necessary. Shanghai’s recent endeavors to become one of the fashion capitals of the world are closely linked to the global shifts of the industry, and the rise of China’s star. Perhaps the re-bundling of the symbolic and material aspects of fashion, along with the restructuring of unsustainable global production networks would create new chances for old and new fashion capitals alike. This, in turn, begs the question of whether we should still think in terms of fashion capitals and cities. Should we rather explore the interrelation of diverse fashion systems and digital spaces, which may, in turn, change our understanding of not just fashion places, but also of fashion itself

Dissipative Landau-Zener transitions of a qubit: bath-specific and universal behavior

We study Landau-Zener transitions in a qubit coupled to a bath at zero temperature. A general formula is derived that is applicable to models with a non-degenerate ground state. We calculate exact transition probabilities for a qubit coupled to either a bosonic or a spin bath. The nature of the baths and the qubit-bath coupling is reflected in the transition probabilities. For diagonal coupling, when the bath causes energy fluctuations of the diabatic qubit states but no transitions between them, the transition probability coincides with the standard LZ probability of an isolated qubit. This result is universal as it does not depend on the specific type of bath. For pure off-diagonal coupling, by contrast, the tunneling probability is sensitive to the coupling strength. We discuss the relevance of our results for experiments on molecular nanomagnets, in circuit QED, and for the fast-pulse readout of superconducting phase qubits.Comment: 16 pages, 8 figure

Photon creation from vacuum and interactions engineering in nonstationary circuit QED

We study theoretically the nonstationary circuit QED system in which the artificial atom transition frequency, or the atom-cavity coupling, have a small periodic time modulation, prescribed externally. The system formed by the atom coupled to a single cavity mode is described by the Rabi Hamiltonian. We show that, in the dispersive regime, when the modulation periodicity is tuned to the `resonances', the system dynamics presents the dynamical Casimir effect, resonant Jaynes-Cummings or resonant Anti-Jaynes-Cummings behaviors, and it can be described by the corresponding effective Hamiltonians. In the resonant atom-cavity regime and under the resonant modulation, the dynamics is similar to the one occurring for a stationary two-level atom in a vibrating cavity, and an entangled state with two photons can be created from vacuum. Moreover, we consider the situation in which the atom-cavity coupling, the atomic frequency, or both have a small nonperiodic time modulation, and show that photons can be created from vacuum in the dispersive regime. Therefore, an analog of the dynamical Casimir effect can be simulated in circuit QED, and several photons, as well as entangled states, can be generated from vacuum due to the anti-rotating term in the Rabi Hamiltonian.Comment: 14 pages, 6 figures. Talk presented at the International Workshop "60 Years of Casimir Effect", 23 - 27 June, 2008, Brasili

Terahertz quantum-cascade lasers for high-resolution absorption spectroscopy of atoms and ions in plasmas

We report on terahertz (THz) quantum-cascade lasers (QCLs) based on GaAs/AlAs heterostructures, which exhibit single-mode emission at 3.360, 3.921, and 4.745 THz. These frequencies are in close correspondence to fine-structure transitions of Al atoms, N+ ions, and O atoms, respectively. Due to the low electrical pump power of these THz QCLs, they can be operated in a mechanical cryocooler in continuous-wave mode, while a sufficient intrinsic tuning range of more than 5 GHz is maintained. The single-mode operation and the intrinsic tuning range of these THz QCLs allow for the application of these lasers as radiation sources for high-resolution absorption spectroscopy to determine the absolute densities of Al atoms, N+ ions, and O atoms in plasmas

Terahertz quantum-cascade lasers for high-resolution absorption spectroscopy of atoms and ions in plasmas

We report on terahertz (THz) quantum-cascade lasers (QCLs) based on GaAs/AlAs heterostructures, which exhibit single-mode emission at 3.360, 3.921, and 4.745 THz. These frequencies are in close correspondence to fine-structure transitions of Al atoms, N+ ions, and O atoms, respectively. Due to the low electrical pump power of these THz QCLs, they can be operated in a mechanical cryocooler in continuous-wave mode, while a sufficient intrinsic tuning range of more than 5 GHz is maintained. The single-mode operation and the intrinsic tuning range of these THz QCLs allow for the application of these lasers as radiation sources for high-resolution absorption spectroscopy to determine the absolute densities of Al atoms, N+ ions, and O atoms in plasmas

Terahertz absorption spectroscopy for measuring atomic oxygen densities in plasmas

This paper describes the first implementation of terahertz (THz) quantum cascade lasers for high-resolution absorption spectroscopy on plasmas. Absolute densities of ground state atomic oxygen were directly obtained by using the fine structure transition at approximately 4.75 THz. Measurements were performed on a low-pressure capacitively coupled radio frequency oxygen discharge. The detection limit in this arrangement was found to be 2 × 10 13 cm−3, while the measurement accuracy was within 5%, as demonstrated by reference measurements of a well-defined ammonia transition. The results show that the presented method is well suited to measure atomic oxygen densities, and it closes the THz gap for quantitative atomic density measurements in harsh environments such as plasmas

Terahertz quantum-cascade lasers for high-resolution absorption spectroscopy of atoms and ions in plasmas

We report on terahertz (THz) quantum-cascade lasers (QCLs) based on GaAs/AlAs heterostructures, which exhibit single-mode emission at 3.360, 3.921, and 4.745 THz. These frequencies are in close correspondence to fine-structure transitions of Al atoms, N+ ions, and O atoms, respectively. Due to the low electrical pump power of these THz QCLs, they can be operated in a mechanical cryocooler in continuous-wave mode, while a sufficient intrinsic tuning range of more than 5 GHz is maintained. The single-mode operation and the intrinsic tuning range of these THz QCLs allow for the application of these lasers as radiation sources for high-resolution absorption spectroscopy to determine the absolute densities of Al atoms, N+ ions, and O atoms in plasmas

Multipole interaction between atoms and their photonic environment

Macroscopic field quantization is presented for a nondispersive photonic dielectric environment, both in the absence and presence of guest atoms. Starting with a minimal-coupling Lagrangian, a careful look at functional derivatives shows how to obtain Maxwell's equations before and after choosing a suitable gauge. A Hamiltonian is derived with a multipolar interaction between the guest atoms and the electromagnetic field. Canonical variables and fields are determined and in particular the field canonically conjugate to the vector potential is identified by functional differentiation as minus the full displacement field. An important result is that inside the dielectric a dipole couples to a field that is neither the (transverse) electric nor the macroscopic displacement field. The dielectric function is different from the bulk dielectric function at the position of the dipole, so that local-field effects must be taken into account.Comment: 17 pages, to be published in Physical Review

Nonlocal response in thin-film waveguides: Loss versus nonlocality and breaking of complementarity

We investigate the effects of nonlocal response on the surface-plasmon polariton guiding properties of the metal-insulator (MI), metal-insulator-metal (MIM), and insulator-metal-insulator (IMI) waveguides. The nonlocal effects are described by a linearized hydrodynamic model, which includes the Thomas-Fermi internal kinetic energy of the free electrons in the metal. We derive the nonlocal dispersion relations of the three waveguide structures taking into account also retardation and interband effects, and examine the delicate interplay between nonlocal response and absorption losses in the metal. We also show that nonlocality breaks the complementarity of the MIM and IMI waveguides found in the non-retarded limit.Comment: 9 pages, 5 figure