Enhanced quantum sensing with multi-level structures of trapped ions

We present a method of enhanced sensing of AC magnetic fields. The method is based on the construction of a robust qubit by the application of continuous driving fields. Specifically, magnetic noise and power fluctuations of the driving fields do not operate within the robust qubit subspace, hence robustness to both external and controller noise is achieved. The scheme is applicable to either a single ion or an ensemble of ions. We consider trapped-ion based implementation via the dipole transitions, which is relevant for several types of ions, such as the ##IMG## [http://ej.iop.org/images/2058-9565/2/3/034006/qstaa771aieqn1.gif] {${}^{40}{\mathrm{Ca}}^{+}$} , ##IMG## [http://ej.iop.org/images/2058-9565/2/3/034006/qstaa771aieqn2.gif] {${}^{88}{\mathrm{Sr}}^{+}$} and the ##IMG## [http://ej.iop.org/images/2058-9565/2/3/034006/qstaa771aieqn3.gif] {${}^{138}{\mathrm{Ba}}^{+}$} ions. Taking experimental errors into acco… …

Read More...

Comments Off on Enhanced quantum sensing with multi-level structures of trapped ions

Enhanced photothermal cooling of nanowires

We investigate the optomechanical interaction between light and metallic nanowires through the action of bolometric forces. We show that the response time of the photothermal forces induced on the nanowire is fast and the strength of the interaction can overcome the radiation pressure force. Furthermore, we suggest the photothermal forces can be enhanced by surface plasmon excitation to cool the sub-megahertz vibrational modes of the nanowires close to its quantum limit. …

Read More...

Comments Off on Enhanced photothermal cooling of nanowires

How Nature Solves Problems Through Computation

The evolutionary biologist Jessica Flack seeks the computational rules that groups of organisms use to solve problems. …

Read More...

Comments Off on How Nature Solves Problems Through Computation

Quantum key distribution network for multiple applications

The fundamental architecture and functions of secure key management in a quantum key distribution (QKD) network with enhanced universal interfaces for smooth key sharing between arbitrary two nodes and enabling multiple secure communication applications are proposed. The proposed architecture consists of three layers: a quantum layer, key management layer and key supply layer. We explain the functions of each layer, the key formats in each layer and the key lifecycle for enabling a practical QKD network. A quantum key distribution-advanced encryption standard (QKD-AES) hybrid system and an encrypted smartphone system were developed as secure communication applications on our QKD network. The validity and usefulness of these systems were demonstrated on the Tokyo QKD Network testbed. …

Read More...

Comments Off on Quantum key distribution network for multiple applications

Quantum emitters coupled to circular nanoantennas for high-brightness quantum light sources

Engineering the directionality and emission rate of quantum light sources is essential in the development of modern quantum applications. In this work we use numerical calculations to optimise the brightness of a broadband quantum emitter positioned in a hybrid metal-dielectric circular periodic nanoantenna. The optimised structure features a photon collection efficiency of ##IMG## [http://ej.iop.org/images/2058-9565/2/3/034004/qstaa73e4ieqn1.gif] {$74 \% $} ( ##IMG## [http://ej.iop.org/images/2058-9565/2/3/034004/qstaa73e4ieqn2.gif] {$82 \% $} ) and a photon flux enhancement of over 10 (6) into a numerical aperture of 0.22 (0.50), respectively, corresponding to a direct coupling into two types of multi-mode fibres. To enhance the emission rate, we present a new circular nanoantenna design where a quantum emitter is attached to a silver nanocone at the centre of the antenna. After optimisation, we find a collection efficiency of ##IMG## …

Read More...

Comments Off on Quantum emitters coupled to circular nanoantennas for high-brightness quantum light sources

Lucky Break Leads to Controversial Supernova Discovery

Supernova hunters were able to train their telescopes on a recent eruption just hours after it exploded. What they found only adds to the growing list of questions surrounding these cosmic blasts. …

Read More...

Comments Off on Lucky Break Leads to Controversial Supernova Discovery

Strange Noise in Gravitational-Wave Data Sparks Debate

The team that discovered gravitational waves put their data online. Now an independent group of researchers claims that they’ve found what might be a serious problem. …

Read More...

Comments Off on Strange Noise in Gravitational-Wave Data Sparks Debate

Can Microbes Encourage Altruism?

If gut bacteria can sway their hosts to be selfless, it could answer a riddle that goes back to Darwin. …

Read More...

Comments Off on Can Microbes Encourage Altruism?