Thanks to their unmatched specificity, nuclear magnetic resonance (NMR) and electron spin resonance (ESR) spectroscopy – jointly referred to as spin-based analytics – are tools of major importance in biology, chemistry, medicine and physics because they allow for the use of a spin (nuclear or electron) as an extremely sensitive, nanoscopic quantum probe of its electronic and magnetic environment inside a molecule. However, their main limitations are high equipment complexity and cost as well as a relatively poor sensitivity due to the very small thermal polarisation of the spin ensembles at room temperature. This poor sensitivity in turn severely compromises the required measurement time, the achievable signal-to-noise ratio and the minimum sample size.
In the proposed talk, we will first introduce the so-called ESR-on-a-chip approach as a new tool in ESR spectroscopy that allows for a CMOS integrated manipulation and detection of electron spins up to very high frequencies in the hundreds of Gigahertz range. We will then discuss the use of nitrogen vacancy (NV) centers in diamond as a potential tool for hyperpolarizing a nuclear spin ensemble at ambient conditions using a laser and the abovementioned ESR-on-a-chip sensors as a compact and cheap, yet high-performance microwave source. Finally, we will introduce the NMR-on-a-chip approach, which integrates an entire NMR spectrometer into a tiny CMOS application specific integrated circuit (ASIC), as a very promising path towards miniaturizing the entire NMR spectrometer including the NV-based hyperpolarization into a compact portable system, which can extend the application range of NMR into entirely new areas including personalized medicine.
We investigate the amount of noise required to turn a universal quantum gate set into one that can be efficiently modelled classically. This question is useful for providing upper bounds on fault tolerant thresholds, and for understanding the nature of the quantum/classical computational transition. We refine some previously known upper bounds using two different strategies. The first one involves the introduction of bi-entangling operations, a class of classically simulatable machines that can generate at most bipartite entanglement. Using this class we show that it is possible to sharpen previously obtained upper bounds in certain cases. As an example, we show that under depolarizing noise on the controlled-not gate, the previously known upper bound of 74% can be sharpened to around 67%. Another interesting consequence is that measurement based schemes cannot work using only 2-qubit non-degenerate projections. In the second strand of the work we utilize the Gottesman-Knill theorem on the classically efficient simulation of Clifford group operations. The bounds attained using this approach for the pi/8-gate can be as low as 15% for general single gate noise, and 30% for dephasing noise.
We present protocol that allows the generation of a maximally
entangled state between individual atoms held in spatially
separate cavities. Under ideal conditions, the scheme is
deterministic. In a realistic setting, when the the atom-cavity
interaction may be weak, and the detectors are imperfect, we show
that the scheme is robust against experimental inefficiencies and
yields probabilistic entanglement of very high fidelity.
Conference Committee Involvement (2)
Fluctuations and Noise in Photonics and Quantum Optics II
26 May 2004 | Maspalomas, Gran Canaria Island, Spain
Fluctuations and Noise in Photonics and Quantum Optics
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.