Topic
Qubit
About: Qubit is a research topic. Over the lifetime, 29978 publications have been published within this topic receiving 723084 citations. The topic is also known as: quantum bit & qbit.
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TL;DR: This work reports on the coherent quantum state transfer from a two-level atomic system to a single photon that enables implementation of distributed quantum networking.
Abstract: Disclosed are apparatus and methods that provide for a coherent quantum state transfer of information from a two-level atomic system (matter) to a single photon (light). Entanglement between a single photon (signal) and a two-component atomic ensemble of cold Rubidium atoms is used to project a quantum memory element (the atomic ensemble) onto any desired state by measuring the signal in a suitable basis. The atomic qubit is read out by stimulating directional emission of a single photon (idler) from the (entangled) collective state of the ensemble. Faithful atomic memory preparation and readout are verified by observed correlations between the signal and idler photons. These results are an important component of distributed quantum networking.
329 citations
TL;DR: It is shown how to realize quantum gates on the spin qubit controlled by the valley bit, making an interplay between the spin and valley as information carriers possible for potential valley-spintronic applications.
Abstract: In monolayer group-VI transition metal dichalcogenides, charge carriers have spin and valley degrees of freedom, both associated with magnetic moments. On the other hand, the layer degree of freedom in multilayers is associated with electrical polarization. Here we show that transition metal dichalcogenide bilayers offer an unprecedented platform to realize a strong coupling between the spin, valley and layer pseudospin of holes. Such coupling gives rise to the spin Hall effect and spin-dependent selection rule for optical transitions in inversion symmetric bilayer and leads to a variety of magnetoelectric effects permitting quantum manipulation of these electronic degrees of freedom. Oscillating electric and magnetic fields can both drive the hole spin resonance where the two fields have valley-dependent interference, making an interplay between the spin and valley as information carriers possible for potential valley-spintronic applications. We show how to realize quantum gates on the spin qubit controlled by the valley bit.
328 citations
TL;DR: In this paper, the spin-dependent long-range interaction known as Rydberg dressing is exploited to entangle a pair of ultracold neutral atoms, which has practical applications in quantum technologies.
Abstract: Tunable interactions in quantum many-body systems have practical applications in quantum technologies. The effective spin-dependent long-range interaction known as Rydberg dressing is now exploited to entangle a pair of ultracold neutral atoms.
327 citations
TL;DR: In this paper, an all-optical spin echo technique was used to increase the decoherence time of a single quantum dot electron spin from nanoseconds to several microseconds.
Abstract: Many proposed photonic quantum networks rely on matter qubits to serve as memory elements1,2. The spin of a single electron confined in a semiconductor quantum dot forms a promising matter qubit that may be interfaced with a photonic network3. Ultrafast optical spin control allows gate operations to be performed on the spin within a picosecond timescale4,5,6,7,8,9,10,11,12,13,14, orders of magnitude faster than microwave or electrical control15,16. One obstacle to storing quantum information in a single quantum dot spin is the apparent nanosecond-timescale dephasing due to slow variations in the background nuclear magnetic field15,16,17. Here we use an ultrafast, all-optical spin echo technique to increase the decoherence time of a single quantum dot electron spin from nanoseconds to several microseconds. The ratio of decoherence time to gate time exceeds 105, suggesting strong promise for future photonic quantum information processors18 and repeater networks1,2. An ultrafast, all-optical spin echo technique is used to increase the decoherence time of a single quantum dot electron spin from nanoseconds to several microseconds. The ratio of decoherence time to gate time exceeds 105, suggesting strong promise for future photonic quantum information processors and repeater networks.
327 citations
TL;DR: An idea to directly encode the qubit of quantum key distributions, and then present a quantum secret sharing scheme where only product states are employed, where the theoretic efficiency is doubled to approach 100%.
327 citations