Interference (wave propagation)

About: Interference (wave propagation) is a research topic. Over the lifetime, 26086 publications have been published within this topic receiving 321110 citations.

Programmable Interference between Two Microwave Quantum Memories

Abstract: New experiments demonstrate on-demand interference between stationary modes stored in separated superconducting microwave cavities, enabling future studies of complex quantum interference phenomena critical to fundamental science and quantum information applications.

Sonoelastographic imaging of interference patterns for estimation of shear velocity distribution in biomaterials

Abstract: The authors have recently demonstrated the shear wave interference patterns created by two coherent vibration sources imaged with the vibration sonoelastography technique. If the two sources vibrate at slightly different frequencies omega and omega+deltaomega, respectively, the interference patterns move at an apparent velocity of (deltaomega/2omega)upsilon(shear), where upsilon(shear) is the shear wave speed. We name the moving interference patterns "crawling waves." In this paper, we extend the techniques to inspect biomaterials with nonuniform stiffness distributions. A relationship between the local crawling wave speed and the local shear wave velocity is derived. In addition, a modified technique is proposed whereby only one shear wave source propagates shear waves into the medium at the frequency omega. The ultrasound probe is externally vibrated at the frequency omega-deltaomega. The resulting field estimated by the ultrasound (US) scanner is proven to be an exact representation of the propagating shear wave field. The authors name the apparent wave motion "holography waves." Real-time video sequences of both types of waves are acquired on various inhomogeneous elastic media. The distribution of the crawling/holographic wave speeds are estimated. The estimated wave speeds correlate with the stiffness distributions.

Aharonov–Bohm interference of fractional quantum Hall edge modes

Abstract: The braiding statistics of certain fractional quantum Hall states can be probed via interferometry of their edge states. Practical difficulties—including loss of phase coherence—make this a challenging task. We demonstrate the operation of a small Fabry–Perot interferometer in which highly coherent Aharonov–Bohm oscillations are observed in the integer and fractional quantum Hall regimes. Careful design of the heterostructure suppresses Coulomb effects and promotes strong phase coherence. We characterize the coherency of edge-mode interference by the energy scale for thermal damping and determine the velocities of the inner and outer edge modes independently via selective backscattering of edge modes originating in the N = 0, 1, 2 Landau levels. We also observe clear Aharonov–Bohm oscillations at fractional filling factors ν = 2/3 and ν = 1/3, which indicates that our device architecture provides a platform for measurement of anyonic braiding statistics. An interferometer device demonstrates the interference of fractional quantum Hall effect edge states. This is a big step towards braiding non-Abelian anyons.

Compute-and-forward: Harnessing interference with structured codes

Abstract: For a centralized encoder and decoder, a channel matrix is simply a set of linear equations that can be transformed into parallel channels. We develop a similar approach to multi-user networks: we view interference as creating linear equations of codewords and that a receiverpsilas goal is to collect a full rank set of such equations. Our new relaying technique, compute-and-forward, uses structured codes to reliably compute functions over channels. This allows the relays to efficiently recover a linear functions of codewords without recovering the individual codewords. Thus, our scheme can work with the structure of the interference while removing the effects of the noise at the relay. We apply our scheme to a Gaussian relay network with interference and achieve better rates than either compress-and-forward or decode-and-forward for certain regimes.

On Mutual Interference Cancellation in a MIMO OFDM Multiuser Radar-Communication Network

Abstract: This paper presents a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) joint radar-communication (RadCom) system and explores its tolerance toward mutual interference. Since OFDM signals are weak toward subcarrier misalignment caused by frequency offsets, some form of interference cancellation will definitely be required for operation in real scenarios. A simple and flexible system level interference cancellation algorithm is proposed, which is to be employed when the radar estimation is no longer reliable. For the proof-of-concept verification, the MIMO RadCom node is implemented on universal software radio peripherals to take hardware imperfections and propagation losses into account. Real-time measurements are also presented to prove the 2D+velocity estimation capability as well as the effectiveness of the interference cancellation algorithm. With this system concept, the dual functions of the RadCom node will be possible in a realistic automotive scenario for vehicle-to-vehicle and vehicle-to-infrastructure communication with the aim of enhancing overall road safety by making driving a collaborative effort instead of an individual one.