IAS Journal Articles
http://hdl.handle.net/10220/11714
2019-03-08T08:31:22ZNonlinear circuit quantum electrodynamics based on the charge-qubit–resonator interface
http://hdl.handle.net/10220/47401
Nonlinear circuit quantum electrodynamics based on the charge-qubit–resonator interface
Yu, Deshui; Kwek, Leong Chuan; Amico, Luigi; Dumke, Rainer
We theoretically explore the applications of a nonlinear circuit QED system, where a charge qubit is inductively coupled to an LC resonator, in the photonic engineering and ultrastrong-coupling multiphoton quantum optics. An arbitrary Fock-state pulsed maser, where the artificial qubit plays the gain-medium role, is achieved via simply sweeping the gate-voltage bias. The resonantly pumped parametric qubit-resonator interface leads to a squeezed intraresonator field, which is utilizable for the quantum-limited microwave amplification. Moreover, upwards and downwards multiphoton quantum jumps may be observed in the driving-free steady-state system.
2018-01-01T00:00:00ZFloquet stroboscopic divisibility in non-Markovian dynamics
http://hdl.handle.net/10220/47346
Floquet stroboscopic divisibility in non-Markovian dynamics
Bastidas, Victor M.; Kyaw, Thi Ha; Tangpanitanon, Jirawat; Romero, Guillermo; Kwek, Leong-Chuan; Angelakis, Dimitris G.
We provide a general description of a time-local master equation for a system coupled to a non-Markovian reservoir based on Floquet theory. This allows us to have a divisible dynamical map at discrete times, which we refer to as Floquet stroboscopic divisibility. We illustrate the theory by considering a harmonic oscillator coupled to both non-Markovian and Markovian baths. Our findings provide us with a theory for the exact calculation of spectral properties of time-local non-Markovian Liouvillian operators, and might shed light on the nature and existence of the steady state in non-Markovian dynamics.
2018-01-01T00:00:00ZSU(3) topological insulators in the honeycomb lattice
http://hdl.handle.net/10220/47327
SU(3) topological insulators in the honeycomb lattice
Bornheimer, U.; Miniatura, Christian; Grémaud, B.
We investigate realizations of topological insulators with spin-1 bosons loaded in a honeycomb optical lattice and subjected to a
SU
(
3
)
spin-orbit coupling—a situation which can be realized experimentally using cold atomic gases. In this paper, we focus on the topological properties of the single-particle band structure, namely, Chern numbers (lattice with periodic boundary conditions) and edge states (lattice with strip geometry) and their connection to time-reversal symmetry and the sublattice symmetry. While
SU
(
2
)
spin-orbit couplings always lead to time-reversal symmetric tight-binding models, and thereby to topologically trivial band structures, suitable
SU
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3
)
spin-orbit couplings can break time-reversal symmetry and lead to topologically nontrivial bulk band structures and to edge states in the strip geometry. In addition, we show that one can trigger a series of topological transitions (i.e., integer changes of the Chern numbers) that are specific to the geometry of the honeycomb lattice by varying a single parameter in the Hamiltonian.
2018-01-01T00:00:00ZQuantum state transmission in a superconducting charge qubit-atom hybrid
http://hdl.handle.net/10220/46735
Quantum state transmission in a superconducting charge qubit-atom hybrid
Yu, Deshui; Valado, María Martínez; Hufnagel, Christoph; Kwek, Leong Chuan; Amico, Luigi; Dumke, Rainer
Hybrids consisting of macroscopic superconducting circuits and microscopic components, such as atoms and spins, have the potential of transmitting an arbitrary state between different quantum species, leading to the prospective of high-speed operation and long-time storage of quantum information. Here we propose a novel hybrid structure, where a neutral-atom qubit directly interfaces with a superconducting charge qubit, to implement the qubit-state transmission. The highly-excited Rydberg atom located inside the gate capacitor strongly affects the behavior of Cooper pairs in the box while the atom in the ground state hardly interferes with the superconducting device. In addition, the DC Stark shift of the atomic states significantly depends on the charge-qubit states. By means of the standard spectroscopic techniques and sweeping the gate voltage bias, we show how to transfer an arbitrary quantum state from the superconducting device to the atom and vice versa.
2016-01-01T00:00:00Z