Coplanar microwave resonators made of 330 nm-thick superconducting YBCO have been realized and characterized in a wide temperature ($T$, 2-100 K) and magnetic field ($B$, 0-7 T) range. The quality factor $Q_L$ exceeds 10$^4$ below 55 K and it slightl
y decreases for increasing fields, remaining 90$%$ of $Q_L(B=0)$ for $B=7$ T and $T=2$ K. These features allow the coherent coupling of resonant photons with a spin ensemble at finite temperature and magnetic field. To demonstrate this, collective strong coupling was achieved by using DPPH organic radical placed at the magnetic antinode of the fundamental mode: the in-plane magnetic field is used to tune the spin frequency gap splitting across the single-mode cavity resonance at 7.75 GHz, where clear anticrossings are observed with a splitting as large as $sim 82$ MHz at $T=2$ K. The spin-cavity collective coupling rate is shown to scale as the square root of the number of active spins in the ensemble.
It is shown that non-centrosymmetric materials with bulk second-order nonlinear susceptibility can be used to generate strongly antibunched radiation at an arbitrary wavelength, solely determined by the resonant behavior of suitably engineered couple
d microcavities. The proposed scheme exploits the unconventional photon blockade of a coherent driving field at the input of a coupled cavity system, where one of the two cavities is engineered to resonate at both fundamental and second harmonic frequencies, respectively. Remarkably, the unconventional blockade mechanism occurs with reasonably low quality factors at both harmonics, and does not require a sharp doubly-resonant condition for the second cavity, thus proving its feasibility with current semiconductor technology.
We present a perturbative approach to derive the semiclassical equations of motion for the two-dimensional electron dynamics under the simultaneous presence of static electric and magnetic fields, where the quantized Hall conductance is known to be d
irectly related to the topological properties of translationally invariant magnetic Bloch bands. In close analogy to this approach, we develop a perturbative theory of two-dimensional photonic transport in gyrotropic photonic crystals to mimic the physics of quantum Hall systems. We show that a suitable permittivity grading of a gyrotropic photonic crystal is able to simulate the simultaneous presence of analog electric and magnetic field forces for photons, and we rigorously derive the topology-related term in the equation for the electromagnetic energy velocity that is formally equivalent to the electronic case. A possible experimental configuration is proposed to observe a bulk photonic analog to the quantum Hall physics in graded gyromagnetic photonic crystals.
We propose the use of nanostructured photonic nanocavities made of second-order nonlinear materials as prospective passive devices to generate strongly sub-Poissonian light via single-photon blockade of an input coherent field. The simplest scheme is
based on the requirement that the nanocavity be doubly resonant, i.e. possess cavity modes with good spatial overlap at both the fundamental and second-harmonic frequencies. We discuss feasibility of this scheme with state-of-the art nanofabrication technology, and the possibility to use it as a passive single-photon source on-demand.
We experimentally characterize the spatial far-field emission profiles for the two lowest confined modes of a photonic crystal cavity of the L3 type, finding a good agreement with FDTD simulations. We then link the far-field profiles to relevant feat
ures of the cavity mode near-fields, using a simple Fabry-Perot resonator model. The effect of disorder on far-field cavity profiles is clarified through comparison between experiments and simulations. These results can be useful for emission engineering from active centers embedded in the cavity.
We present a theory of the quantum vacuum radiation that is generated by a fast modulation of the vacuum Rabi frequency of a single two-level system strongly coupled to a single cavity mode. The dissipative dynamics of the Jaynes-Cummings model in th
e presence of anti-rotating wave terms is described by a generalized master equation including non-Markovian terms. Peculiar spectral properties and significant extracavity quantum vacuum radiation output are predicted for state-of-the-art circuit cavity quantum electrodynamics systems with superconducting qubits.
