The authors present experimental results, and a supporting theory, showing that one-dimensional system in which transport is ballistic possesses quantised resistance, h/2ie2, where i the number of occupied 1D sub-bands spin degeneracy two. A short narrow channel defined 2DEG GaAs-AlGaAs heterojunction as width changed, pass through Fermi energy resistance jumps between values. value derived accuracy quantisation discussed. effect can be strong at temperatures approximately 0.1 K, with up to...

Brownian heat engines use local temperature gradients in asymmetric potentials to move particles against an external force. The energy efficiency of such machines is generally limited by irreversible flow carried that make contact with different baths. Here we show that, using a suitably chosen filter, electrons can be transferred reversibly between reservoirs have temperatures and electrochemical potentials. We apply this result propose based on mesoscopic semiconductor ratchets, which...

Adiabatically rocked electron ratchets, defined by quantum confinement in semiconductor heterostructures, were experimentally studied a regime where tunneling contributed to the particle flow. The rocking-induced flow reverses direction as function of temperature. This result confirms recent prediction fundamentally different behavior classical versus ratchets. A wave-mechanical model reproduced temperature-induced current reversal and provides an intuitive explanation.

Pursuit-evasion is the problem of capturing mobile targets with one or more pursuers. We use deep reinforcement learning for pursuing an omni-directional target multiple, homogeneous agents that are subject to unicycle kinematic constraints. shared experience train a policy given number pursuers executed independently by each agent at run-time. The training benefits from curriculum learning, sweeping-angle ordering locally represent neighboring and encouraging good formations reward...

We present an approach for safe, and object-independent human-to-robot handovers using real time robotic vision, manipulation. aim general applicability with a generic object detector, fast grasp selection algorithm, by single gripper-mounted RGB-D camera, hence not relying on external sensors. The robot is controlled via visual servoing towards the of interest. Putting high emphasis safety, we use two perception modules: human body part segmentation, hand/finger segmentation. Pixels that...

We have measured the Hall voltage developed across a narrow, high-mobility two-dimensional electron gas of variable width. For narrow channels, vanishes when prependicular magnetic field is reduced below certain, critical value. If kept constant as width channel reduced, shows large departures from classically expected result.

We investigate the transition to a Sinai geometry by introducing circular pattern at center of square mesoscopic billiard defined in high quality AlGaAs/GaAs crystal. The induces novel quantum interference structure magnetoresistance with characteristic field scale over an order magnitude smaller than previously reported billiards. A systematic comparison fine and coarse structures, which differ scale, demonstrates first observation geometry-induced ``self-similarity'' semiconductor system.

Micron-sized loops of high-mobility two-dimensional electron gas have been made on GaAs-AlGaAs heterostructures using a novel split-gate technique. Aharonov–Bohm oscillations amplitude up to 20% the device resistance observed at very low temperatures (T<100 mK), together with h/2e which appear be due interference between pairs time-reversed paths near B=0. The h/e period is found vary by ∼25% magnetic field, possibly as result formation edge states. In quantum Hall effect, plateaus in...

Band-gap photoluminescence (PL) is used to establish the optical signature of a GaAs-${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Al}}_{\mathit{x}}$As heterojunction in extreme quantum limit. The temperature and field dependence new PL structure maps phase boundary which correlates with electron liquid-solid transition.

Humans are highly skilled in communicating their intent for when and where a handover would occur. However, even the state-of-the-art robotic implementations handovers typically lack of such communication skills. This study investigates visualization robot's internal state Human-to-Robot Handovers using Augmented Reality. Specifically, we explore use visualized 3D models object gripper to communicate estimation is pose which robot intends grasp object. We tested this design via user with 16...

Micrometer-sized loops of two-dimensional electron gas have been made on GaAs-AlGaAs heterostructures by electrostatic confinement. A split gate is used to define the loop, allowing width conducting channels be varied changing voltage. The magnetoresistance has measured at low temperatures (T<100 mK) and shows strong Aharonov-Bohm oscillations with amplitudes up 7% total resistance in narrowest devices. are out B approximately=0.5 T then die as increases approximately=1 T, a possible...

With the increasing availability of head-mounted displays for virtual reality and augmented reality, we can create immersive maps in which user is closer to data. Embodiment a key concept, allowing act upon objects an environment. Our work explores use embodied interaction maps. We propose four design considerations gesture with maps: object presence, consistent physics, human body skills, direct manipulation. present example flow map series novel interactions, adhere proposed...

We have investigated the magnetoresistance of a heterostructure containing near surface two-dimensional electron gas subject to periodic magnetic field that alternates in sign. The is produced by an array submicrometer ferromagnets fabricated on heterostructure. observe giant low-field due electrons propagating open orbits along lines zero field. are able account for observed form and magnitude this semiclassical model.

Experimental evidence is presented for the appearance of new plateaux in differential conductance a ballistic 1D channel high DC bias regime. In zero magnetic field, authors observe steps conduction e2/h, as opposed to conventional value 2e2/h spin-degenerate subband. The are found be at quantised values an accuracy few per cent and described well by model that assumes dropped symmetrically channel. addition, all disappear with increasing voltage which can explained terms enhancement...

The authors have defined, in parallel configuration, two split gate devices 0.3 mu m long by wide with a centre-to-centre separation of 0.5 on high mobility heterojunction. At low temperatures, when the phase coherence length is longer than channel length, conduction through each one ballistic and shows steps conductance 2e2/h. If also greater separation, transport both channels no independent, but instead act co-operatively, leading to coherent 4e2/h; this can be seen even if do not same...

The authors have fabricated a 2D array of 1D narrow channels in square lattice configuration on high mobility GaAs/GaAlAs heterostructure. When gate voltage is applied the underlying two-dimensional electron gas depleted creating 4000 dots, size 0.2 mu m, leaving grid-like conducting path quasi one-dimensional that are linked every 0.5 m. For low values magnetic field Hall measured either side device quenched across its entire width 25 longitudinal magneto-resistance reveals Aharonov-Bohm...

Highly aligned conducting polymer nanowires have been grown between two nanometer-scale metal electrodes, providing a simple way to incorporate single and multiple into pre-patterned electrical circuits. A highly sensitive nanowire chemical sensor has fabricated as proof-of-concept of this method we report results concerning the exposure ammonia gas.

We investigate how fractals evolve into nonfractal behavior as the generation process is gradually suppressed. Fractals observed in conductance of semiconductor billiards are particular interest because semiclassical and can be suppressed by transitions towards either fully classical or quantum-mechanical conduction. Investigating a range billiards, we identify "universal" changeover from fractal to conductance, which described smooth evolution rather than deterioration scaling properties.

A sharp step-like structure, which is seen in the current-voltage characteristic of a laterally confined AlGaAs/GaAs resonant tunnelling novel manifestation quantum effect arising when one-dimensional wires feed electrons into zero-dimensional box. The authors can analyse data to deduce time, an inelastic scattering time and transmission probability for this system. height current steps, Delta I, gives electron taue, via I=e/2 while differential conductance peak probability, T0, G...

We present results on the magnetic-field-induced metal-insulator transition in compensated GaAs. The electrical conductivity was found to obey $\ensuremath{\sigma}=a+b{T}^{\frac{1}{3}}$ down 60 mK, both sides of transition, where $a$ and $b$ were constant for a given magnetic field. This indicates that is determined by shortest length scale, this case interaction length, metallic insulating transition. Thus, behavior essentially unchanged as scanned, long one scale dominates.

The authors have investigated magneto-transport through a lateral quantum box defined by patterned Schottky barrier on GaAs-AlGaAs heterojunction. As the size of box, and reflecting potential, are varied, edge states successively reflected with consequent change in value plateaux resistance. Superimposed plateau modulations resistance having both electrical magnetic origin. Resonant transport, an increase transmission ratio to unity, (corresponding oscillations at, or above, values), occurs...