General Biophysics News

Deterministic quantum teleportation between distant atomic objects Original Source >  

Quantum teleportation of discrete and continuous is the transfer of a quantum mechanical state without the transmission of a physical system carrying this state.

Quantum teleportation is a key ingredient of quantum networks [1, 2] and a building block for quantum computation [3, 4]. Teleportation between distant material objects using light as the quantum information carrier has been a particularly exciting goal. Here we propose and demonstrate a new element of the quantum teleportation landscape, the deterministic continuous variable teleportation between distant material objects. The objects are macroscopic atomic ensembles at room temperature. Entanglement required for teleportation is distributed by light propagating from one ensemble to the other. We demonstrate that the experimental fidelity of the quantum teleportation is higher than that achievable by any classical process. Furthermore, we demonstrate the benefits of deterministic teleportation by teleporting a sequence of spin states evolving in time from one distant object onto another. The teleportation protocol is applicable to other important systems, such as mechanical oscillators coupled to light or cold spin ensembles coupled to microwaves.


Science Daily Reported on this article on June 6, 2013:

Diffusion Magnetic Resonance Imaging: What Water Tells Us about Biological Tissues Original Source >  

What Water Tells Us about Biological TissuesSince its introduction in the mid-1980s, diffusion magnetic resonance imaging (MRI), which measures the random motion of water molecules in tissues, revealing their microarchitecture, has become a pillar of modern neuroimaging. Its main clinical domain has been the diagnosis of acute brain stroke and neurogical disorders, but it is also used in the body for the detection and management of cancer lesions. It can also produce stunning maps of white matter tracks in the brain, with the potential to aid in the understanding of some psychiatric disorders. However, in order to exploit fully the potential of this method, a deeper understanding of the mechanisms that govern the diffusion of water in tissues is needed.

Increase in Short-Interval Intracortical Facilitation of the Motor Cortex after Low-Frequency Repetitive Magnetic Stimulation of the Unaffected Hemisphere in the Subacute Phase after Stroke Original Source >  

Interval Intracortical Facilitation of the Motor Cortex after Low-Frequency Repetitive Magnetic

Low-frequency repetitive transcranial magnetic stimulation of the unaffected hemisphere (UH-LF-rTMS) in patients with stroke can decrease interhemispheric inhibition from the unaffected to the affected hemisphere and improve hand dexterity and strength of the paretic hand. The objective of this proof-of-principle study was to explore, for the first time, effects of UH-LF-rTMS as add-on therapy to motor rehabilitation on short-term intracortical inhibition (SICI) and intracortical facilitation (ICF) of the motor cortex of the unaffected hemisphere () in patients with ischemic stroke. Eighteen patients were randomized to receive, immediately before rehabilitation treatment, either active or sham UH-LF-rTMS, during two weeks. Resting motor threshold (rMT), SICI, and ICF were measured in before the first session and after the last session of treatment. There was a significant increase in ICF in the active group compared to the sham group after treatment, and there was no significant differences in changes in rMT or SICI. ICF is a measure of intracortical synaptic excitability, with a relative contribution of spinal mechanisms. ICF is typically upregulated by glutamatergic agonists and downregulated by gabaergic antagonists. The observed increase in ICF in the active group, in this hypothesis-generating study, may be related to reorganization induced by UH-LF-rTMS.

Medical Applications of Electromagnetic Fields Original Source >  

In this article, we describe two possible applications of low-intensity non-ionizing electromagnetic fields (EMF) for the treatment of malaria and cancer, respectively. In malaria treatment, a low-intensity extremely-low frequency magnetic field can be used to induce vibration of hemozoin, a super-paramagnetic polymer particle, inside malaria parasites. This disturbance could cause free radical and mechanical damages leading to the death of the parasite. This concept has been tested in vitro on malaria parasites and found to be effective. This may provide a low cost effective treatment for malaria infection in humans. The rationale for cancer treatment using low-intensity EMF is based on two concepts that have been well established in the literature: (1) low-intensity non-thermal EMF enhances cytotoxic free radicals via the iron-mediated Fenton reaction; and (2) cancer cells have higher amounts of free iron, thus are more susceptible to the cytotoxic effects of EMF. Since normal cells contain minimal amount of free iron, the effect would be selectively targeting cancer cells. Thus, no adverse side effect would be expected as in traditional chemotherapy and radiation therapy. This concept has also been tested on human cancer cell and normal cells in vitro and proved to be feasible.

Quantum teleportation over 100  km of fiber using highly efficient superconducting nano-wire single-photon detectors Original Source >  

Quantum teleportation is an essential quantum operation by which we can transfer an unknown quantum state to a remote location with the help of quantum entanglement and classical communication. Since the first experimental demonstrations using photonic qubits and continuous variables, the distance of photonic quantum teleportation over free-space channels has continued to increase and has reached >100  km. On the other hand, quantum teleportation over optical fiber has been challenging, mainly because the multifold photon detection that inevitably accompanies quantum teleportation experiments has been very inefficient due to the relatively low detection efficiencies of typical telecom-band single-photon detectors. Here, we report on quantum teleportation over optical fiber using four high-detection-efficiency superconducting nanowire single-photon detectors (SNSPDs). These SNSPDs make it possible to perform highly efficient multifold photon measurements, allowing us to confirm that the quantum states of input photons were successfully teleported over 100 km of fiber with an average fidelity of 83.7±2.0%.

© 2015 Optical Society of America

Technical Parameters for Laser Acupuncture to Elicit Peripheral and Central Effects: State-of-the-Art and Short Guidelines Based on Results from the Medical University of Graz, the German Academy of Acupuncture, and the Scientific Literature Original Source >  

The scientific literature in the area of laser acupuncture is rather large; however, the actual mechanisms and effects have not yet been proven in detail. Since the early days of laser acupuncture, there are still many open questions concerning technical parameters of this innovative technique. In this paper, we report about the most important technical parameters (wavelength, output power, power density, energy density, dose range, and continuous or pulsed laser) for laser acupuncture and present quantitative results for optimal laser stimulation, which allow eliciting reproducible effects in the periphery and in the brain. There are several position statements on laser acupuncture and also several review articles in scientific literature concerning clinical effectiveness of laser acupuncture. For example, the Australian Medical Acupuncture College stated recently that “the optimal energy density for laser acupuncture and biostimulation, based on current clinical experience, is 4 J/cm2”. However, our results of previous research studies and of this paper clearly show that dose must be adjusted according to the individual responses.

The Rising Tide of tDCS (transcranial direct current stimulation) in the Media and Academic Literature Original Source >  

By: Veljko Dubljevic, Victoria Saigle, and Eric Racine

Abstract: Academic and public interest in tDCS has been fueled by strong claims of therapeutic and enhancement effects. We report a rising tide of tDCS coverage in the media, while regulatory action is lacking and ethical issues need to be addressed.

Introduction: Neurostimulation has a long history of attracting academic and public attention. The Egyptians knew about the electric properties of catfish (Finger, 1994), but it is unclear if (and how) they experimented with them for clinical purposes. Both Plato and Aristotle described the ability of the torpedo fish to generate numbing effects via its electric discharge (Finger, 1994). Later writings from Scribonius Largus, Pliny the Elder, and Galen of Pergamum detail the use of live torpedo fish to treat headaches (Priori, 2003). The Romans went beyond scholarly interest by cultivating the fish for explicit therapeutic purposes, as evidenced by a frescoed store front that marketed their use to the public in Pompeii (Finger, 1994). Other therapeutic uses of brain stimulation were reported by Ibn-Sidah, an 11th century physician, who suggested using an electric catfish to treat epilepsy (Brunoni et al., 2012). With the advent of electrophysiology in the 1700s, direct current began to be used in clinical settings for the treatment of melancholia (Priori, 2003). These advances drew significant public interest and generated discussion about their philosophical and ethical implications (e.g., Shelley’s Frankenstein).

Transcranial Magnetic Stimulation: Disrupting Neural Activity to Alter and Assess Brain Function Original Source >  

Transcranial magnetic stimulation (TMS), first successfully demonstrated in 1985 (Barker et al., 1985), is a very safe, when following current safety guidelines (Rossi et al., 2009), and noninvasive method for affecting brain function. It relies upon the properties of electromagnetic induction; a rapidly changing magnetic field is generated when a high-voltage current is passed through a coil. When this coil is held in close proximity to any electrically conducting medium, such as the brain, this time-varying magnetic field induces current in a direction opposite to the original current in the coil (Fig. 1).

Figure 1.

When a strong, rapid current is passed through a stimulating coil (top), a rapidly changing magnetic field is produced, which induces current into the brain (bottom).

As a result of this ion flow, action potentials are triggered in neurons that are within the induced current field, along with a subsequent period of deactivation, presumably through prolonged IPSPs. Because normal ongoing brain activity is disrupted by this induced current, TMS provides a way for investigators to produce a transient and reversible period of brain disruption or “virtual lesion.” Thus, unlike other experimental techniques [e.g., functional magnetic resonance imaging (fMRI), electroencephalography (EEG)/event-related potentials (ERPs)], TMS can assess whether a given brain area is necessary for a given function rather than simply correlated with it.