2,343 research outputs found
The generalized 3-edge-connectivity of lexicographic product graphs
The generalized -edge-connectivity of a graph is a
generalization of the concept of edge-connectivity. The lexicographic product
of two graphs and , denoted by , is an important graph
product. In this paper, we mainly study the generalized 3-edge-connectivity of
, and get upper and lower bounds of .
Moreover, all bounds are sharp.Comment: 14 page
Entangling interactions between artificial atoms mediated by a multimode left-handed superconducting ring resonator
Superconducting metamaterial transmission lines implemented with lumped
circuit elements can exhibit left-handed dispersion, where the group and phase
velocity have opposite sign, in a frequency range relevant for superconducting
artificial atoms. Forming such a metamaterial transmission line into a ring and
coupling it to qubits at different points around the ring results in a
multimode bus resonator with a compact footprint. Using flux-tunable qubits, we
characterize and theoretically model the variation in the coupling strength
between the two qubits and each of the ring resonator modes. Although the
qubits have negligible direct coupling between them, their interactions with
the multimode ring resonator result in both a transverse exchange coupling and
a higher order interaction between the qubits. As we vary the detuning
between the qubits and their frequency relative to the ring resonator modes, we
observe significant variations in both of these inter-qubit interactions,
including zero crossings and changes of sign. The ability to modulate
interaction terms such as the scale between zero and large values for
small changes in qubit frequency provides a promising pathway for implementing
entangling gates in a system capable of hosting many qubits.Comment: 8 + 11 pages, 5 + 5 figures, 0 + 3 table
A time-domain control signal detection technique for OFDM
Transmission of system-critical control information plays a key role in efficient management of limited wireless network resources and successful reception of payload data information. This paper uses an orthogonal frequency division multiplexing (OFDM) architecture to investigate the detection performance of a time-domain approach used to detect deterministic control signalling information. It considers a type of control information chosen from a finite set of information, which is known at both transmitting and receiving wireless terminals. Unlike the maximum likelihood (ML) estimation method, which is often used, the time-domain detection technique requires no channel estimation and no pilots as it uses a form of time-domain correlation as the means of detection. Results show that when compared with the ML method, the time-domain approach improves detection performance even in the presence of synchronisation error caused by carrier frequency offset
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