Yanhua Shih

Superresolution via structured illumination quantum correlation microscopy (Conference Presentation)

We propose to use intensity correlation microscopy in combination with structured illumination to image quantum emitters that exhibit antibunching with a spatial resolution reaching far into the sub-classical regime. Combining intensity measurements and intensity auto correlations up to order m creates an effective PSF with FWHM shrunk by the factor p m. Structured Illumination microscopy on the other hand introduces a resolution improvement of factor 2 by use of the principle of moire fringes. Here, we show that for linear low-intensity excitation and linear optical detection the simultaneous use of both techniques leads to an in theory unlimited resolution power with the improvement scaling favorably as m+sqrt m in dependence of the correlation order m. Hence, yielding this technique to be of the utmost interest for biological imaging. We present the underlying theory and simulations demonstrating the highly increased spatial superresolution, and point out requirements for an experimental implementation.

Cancelling out aberrations through high order correlations (Conference Presentation)

The imaging through optical systems may have distortions called aberrations. It can be chromatic aberrations, an effect resulting from dispersion due to the impossibility to focus all colors to the same point or monochromatic aberrations, where the rays emerging from one object point will not all meet at a single image point. Thanks to an analogy between the quantum and classical intensity light correlations, the previous studies explored the ghost imaging under both viewpoint. Although, the first approach was the use of correlated-photon imaging for the cancellation of phase aberrations, some authors have suggested theoretical models for the cancellation of phase aberrations using classical light in the ghost-imaging scheme. However, a detailed experimental study of the cancelation of phase aberrations using classical light intensity correlation is still missing in the literature. In this work, we show that exploring correlations of fluctuations in speckle intensity it is possible to cancel out aberrations that may exist in the Fraunhofer plane of an optical system. The aberrations cancelation occurs independently of its shape and it does not need coordinate inversion. We use high-order intensity correlations to obtain high visibility. Therefore, we extended the quantum-classical analogy to the study of cancelation of phase aberrations showing an interesting and useful distinction from the quantum case. It is possible to embed images into speckle patterns, and to recover it though the spatial correlation function. Therefore, this effect can be useful in imaging through random media and microscopy, canceling inherent aberrations than can cause distortions in the image.

On photonic spectral entanglement improving quantum communication (Conference Presentation)

Let us consider the experimental setup where SPDC source generates photon pairs which are subsequently coupled to single-mode fibers (SMFs). We assume that there are three parties involved: 1) Alice, possessing the photon pair source, detection system and the fiber connecting them, 2) Bob, who monitors the output of the second, long-distance fiber and 3) Eve, who can perform the most general collective attacks in order to acquire information which Alice and Bob wish to transfer. Typically, in fiber-based communication the chromatic dispersion is considered to be an obstacle, limiting the maximal distance at which information carrier can be securely transmitted. This phenomenon forces the trusted parties to define longer detection windows to avoid losing signal photons and increases the amount of detection noise that is being registered. We consider standard BB84 quantum key distribution protocol, based on the SPDC source located in between Alice and Bob. The parameters of standard realistic telecommunication fibers (SMF28e+) are take into account. The source emits photon which apart of being entangled in polarization degree of freedom are entangled in spectral domain. This is the key feature which allows one to reduce detection noise by manipulating the spectral correlation between the produced photons. In this way the maximal security distance can be increased by around 10%.

Future outlook for diamond-based quantum information devices (Conference Presentation)

In recent years there has been substantial progress in solid-state quantum information demonstrations based on diamond. This ranges from room-temperature multi-qubit quantum registers to spin-photon entanglement to loophole-free Bell tests. Most of these demonstrations are done with the nitrogen-vacancy (NV) center. Recently however the silicon-vacancy (SiV) center has shown a much better coupling to photons, owing to the suppression of spectral diffusion. Still more recently the germanium-vacancy (GeV) has shown much higher quantum efficiency the SiV. However there are tradeoffs. In this talk I will review the various options for quantum information devices in diamond. I will also discuss new options for the future, including designer color centers made possible by novel diamond growth techniques.

A quantum repeater network formed with hybrid NV diamond modules(Conference Presentation)

We present new quantum repeater architectures based on optical modules with NV diamond centers to highlight how physical properties of these optical modules change the operations, performance and limitations of the quantum repeater systems.We focus on two different approaches to construct optical modules, and see how the properties of modules propagate to the total system. The first approach to construct the optical module is to utilize the conditional refection dependent on the electron state of the single NV center in the cavity, and the other approach is to use absorption induced teleportation from an incoming photon to the nuclear spin of the NV center. To characterize a quantum repeater system, the processes and protocols associated with photons are important.As photons are not reliable as an information carrier, i.e. quantum manipulations associated with photons are not deterministic, and the protocols and manipulations rely on post-selection to keep the fidelity of the quantum information.Post-selection is essential in quantum communications based on photons to maintain the fidelity of the communication, however it restricts the architecture of the system to be tolerant to probabilistic gates. This factor is cost intensive and is the key for the architectures to be scalable.We show that the details of how the scalability of the architectures can be affected by physical parameters of the modules.