Science Daily March 14, 2018 Researchers in Italy have demonstrated that hexagonal graphene nanoflakes with zigzag edges display quantum interference. In “Quantum interference transistors” destructive interference would be the “OFF” status. For the “ON” status, they say it is sufficient to remove the conditions for interference. They also demonstrated that magnetism emerges spontaneously at their edges, without any external intervention. This enables the creation of a spin current. The union between the phenomena of quantum interference and of magnetism would allow to obtain almost complete spin polarization, with a huge potential in the field of spintronics. These properties could be […]
Category Archives: Quantum science
Magnon spin currents can be controlled via spin valve structure
Physorg March 15, 2018 In contrast to electrical currents magnon spin currents conduct magnetic momenta. One fundamental building block of magnon spintronics is magnon logic, by which logic operations are processed by the superposition of spin currents. An international team of researchers (Germany, Japan) reports on magnetization orientation-dependent spin current detection signals in collinear magnetic multilayers inspired by the functionality of a conventional spin valve. This yielded a spin valve-like behavior with an amplitude change of 120% in their systems… read more. Open access TECHNICAL ARTICLE
Scaling silicon quantum photonic technology
Physorg March 9, 2018 An international team of researchers (UK, China, Denmark, Germany, Poland, Spain) has demonstrated a programmable path-encoded multidimensional entangled system with dimension up to 15×15, where two photons exist over 15 optical paths at the same time and are entangled with each other. This multidimensional entanglement is realised by exploiting silicon-photonics quantum circuits, integrating in a single chip, 550 optical components, including 16 identical photon-pair sources, 93 optical phase-shifters, 122 beam-splitters. The research provides a clear path to scaling up to the many millions of components that are ultimately needed for large-scale quantum computing applications… read more. […]
Scientists gain new visibility into quantum information transfer
MIT News March 8, 2018 A team of researchers in the US (MIT, Dartmouth College) combined NMR techniques with their knowledge of the spin dynamics in their crystal, whose geometry approximately confines the evolution to linear spin chains. It allowed them to figure out a metric, average correlation length, for how many spins are connected to each other in a chain and determine if the interaction is winning or disorder is winning keeping the system in a more quantum localized state. The method represents a possible advance toward the ability to control localization. Because many-body localization preserves information and prevents […]
Approximate quantum cloning: The new way of eavesdropping in quantum cryptography
Physorg February 20, 2018 Uncertainty at the quantum scale makes exact cloning of quantum states impossible. Yet, they may be copied in an approximate way using probabilistic quantum cloning. Continuing previous work, researchers in China showed that if an independent subset cannot be expressed as the superposition of the other states in the set, then these dependent states can be partially cloned. Cloning operation allows scientists to make many copies of the output of computations—which take the form of unitary operations. These can, in turn, be used as input and fed into various further processes. Cloning also has applications in […]
‘Two-way signaling’ possible with a single quantum particle
Physorg February 26, 2018 By using a quantum particle that has been put in a superposition of two different locations, researchers in Austria have theoretically shown that both partners are able to encode their messages into a single quantum particle simultaneously. Being in a quantum superposition means that the quantum particle is “simultaneously present” at each partner’s location. Therefore, both partners are able to encode their messages into a single quantum particle simultaneously, a task that is essentially impossible using classical physics. The experimental results show that the communication is secure and anonymous, the direction of communication is hidden—an eavesdropper […]
Major discovery in controlling quantum states of single atoms
Science Daily February 16, 2018 To protect the quantum properties of a spin, control over its local environment, including energy relaxation and decoherence processes, is crucial. An international team of researchers (South Korea, USA – industry, Germany, Switzerland, Portugal, Spain) was able to precisely image individual iron atoms and measure and control the time that the iron atom can maintain its quantum behavior. They showed that the loss in quantum state superposition is mainly caused by nearby electrons that the researchers injected with extreme control into the iron atom. Understanding these destructive interactions allows us to avoid them in future […]
Physicists create new form of light
MIT News February 15, 2018 A team of researchers in the US (MIT, Harvard University, Princeton University, NITS, University of Chicago) has observed groups of three photons interacting and, in effect, sticking together to form a completely new kind of photonic matter. In controlled experiments, the researchers found that when they shone a very weak laser beam through a dense cloud of ultracold rubidium atoms, rather than exiting the cloud as single, randomly spaced photons, the photons bound together in pairs or triplets, suggesting some kind of interaction — in this case, attraction — taking place among them. According to […]
Light controls two-atom quantum computation
Nanowerk February 7, 2018 In the new concept for quantum gate demonstrated by researchers in Germany, photons impinging on an optical cavity mediate an interaction between two atoms trapped inside. This interaction is the basis for performing characteristic gate operations between the atoms. The gate operations take place within microseconds and the gate mechanism can be applied to other experimental platforms, and the two-atom gate can serve as a building block in a quantum repeater… read more. Open Access TECHNICAL ARTICLE
The quantum internet has arrived (and it hasn’t)
Nature February 14, 2018 Researchers in the Netherlands argue that they could use quantum mechanics to do much more, by harnessing nature’s uncanny ability to link or entangle distant objects, and teleporting information between them. They have already started to build the first genuine quantum network, which will link four cities in the Netherlands. The project, set to be finished in 2020, could be the quantum version of ARPANET. The lead scientist is also coordinating a larger European project, called the Quantum Internet Alliance, which aims to expand the Dutch experiment to a continental scale… read more