quantum steering

Top PDF quantum steering:

Quantum steering ellipsoids, extremal physical states and monogamy

Quantum steering ellipsoids, extremal physical states and monogamy

The term ‘ steering ’ was originally used by Schrödinger [10] in the context of his study into the complete set of states/ensembles that a remote system could be collapsed to, given some (pure) initial entangled state. The steering ellipsoid we study is the natural extension of that work to mixed states (of qubits). Schrödinger was motivated to perform such a characterisation by the EPR paper [11]. The question of whether the ensembles one steers to are consistent with a local quantum model has been recently formalised [12] into a criterion for ‘ EPR steerability ’ that provides a distinct notion of nonlocality to that of entanglement: the EPR-steerable states are a strict subset of the entangled states. We note that the existence of a steering ellipsoid with nonzero volume is necessary, but not suf fi cient, for a demonstration of EPR-steering. It is an open question whether the quantum steering ellipsoid can provide a geometric intuition for EPR-steerable states as it can for separable, entangled and discordant states, although progress has recently been made [13].

21 Read more

Quantum Steering Ellipsoids

Quantum Steering Ellipsoids

Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2 L 2Y5, Canada (Received 13 May 2013; revised manuscript received 6 December 2013; published 8 July 2014) The quantum steering ellipsoid of a two-qubit state is the set of Bloch vectors that Bob can collapse Alice ’ s qubit to, considering all possible measurements on his qubit. We provide an elementary construction of the ellipsoid for arbitrary states, calculate its volume, and explain how this geometric representation can be made faithful. The representation provides a range of new results, and uncovers new features, such as the existence of “ incomplete steering ” in separable states. We show that entanglement can be analyzed in terms of three geometric features of the ellipsoid and prove that a state is separable if and only if it obeys a “ nested tetrahedron ” condition.

5 Read more

Quantification of Gaussian quantum steering

Quantification of Gaussian quantum steering

Quantum correlations have been intensively investigated in recent years after the realization that, besides their foundational importance, they can be exploited to outperform any classical approach in certain tasks, e.g., in computation [1], secure communication [2,3], and metrology [4]. For mixed states of composite quantum systems, quantum correlations can manifest in different forms [5]. While entanglement [6] and Bell nonlocality [7] are two of the most well-studied such manifestations, an intermediate type of quantum correlation, known as quantum steering [8,9], has only quite recently attracted a renewed interest from the quantum information community [10,11], opening new avenues for theoretical exploration and practical applications. Steering is the quantum mechanical phenomenon that allows one party, Alice, to change (i.e., to “steer”) the state of a distant party, Bob, by exploiting their shared entan- glement. This phenomenon, fascinatingly discussed by Schrödinger [8,9], was already noted by Einstein, Podolksy, and Rosen (EPR) in their famous 1935 paper [12], and is at the heart of the so-called EPR paradox [13]. There it was argued that steering implied an unacceptable “action at a distance,” which led EPR to claim the incom- pleteness of quantum theory. The EPR expectations for local realism were mostly extinguished by Bell ’ s theorems [14,15], which showed that no locally causal theory can reproduce all the correlations observed in nature [16]. The first experimental criterion for the demonstration of the EPR paradox, i.e., for the detection of quantum steering, was later proposed by Reid [17], but it was not until 2007 that the particular type of nonlocality captured by the concept of steering [8,9,12] was in fact formalized [10,18].

6 Read more

A formalism for steering with local quantum measurements

A formalism for steering with local quantum measurements

The question of how to best understand post-quantum steering, including its possibilities and its limitations —which could ultimately lead to an information-theoretic reason why post-quantum steering does not appear in nature — is still open. One main reason for this is the lack of a framework within which to study quantum as well as post-quantum steering in a unified manner. This makes the implications of post-quantum steering difficult to address. We cannot take a black-box approach—that is, based solely on the use of conditional probability distributions, as in the case of Bell non-locality — since there is the assumption that one or more parties have a quantum system and their devices are well-characterised. Nevertheless, in the steering framework there is a natural analogue to conditional probability distributions: the assemblage. The latter is the collection of states of the characterised parties for each possible measurement outcome of measurements made by the uncharacterised systems. Another obstacle on the path towards understanding the power of post-quantum steering in information tasks is the lack of examples of ( large families of ) post-quantum steering assemblages.

17 Read more

Multipartite Gaussian steering: monogamy constraints and quantum cryptography applications

Multipartite Gaussian steering: monogamy constraints and quantum cryptography applications

With the imminent debacle of Moore’s law, and the con- stant need for faster and more reliable processing of infor- mation, quantum technologies are set to radically change the landscape of modern communication and computation. A suc- cessful and secure quantum network relies on quantum corre- lations distributed and shared over many sites [1]. Di ff erent kinds of multipartite quantum correlations have been consid- ered as valuable resources for various applications in quan- tum communication tasks. Multipartite entanglement [2–8] and multipartite Bell nonlocality [9–12] are two well known instances and have received extensive attention in recent de- velopments of quantum information theory, as well as in other branches of modern physics. There has been substantial ex- perimental progress in engineering and detection of both such correlations, by using e.g. photons [13–17], ions [18], or con- tinuous variable (CV) systems [19–22]. However, as an inter- mediate type of quantum correlation between entanglement and Bell nonlocality, multipartite quantum steering [23, 24] still defies a complete understanding. In consideration of the intrinsic relevance of the notion of steering to the founda- tional core of quantum mechanics, it has become a worth- while objective to deeply explore the characteristics of multi- partite steering distributed over many parties, and to establish what usefulness to multiuser quantum communication proto- cols can such a resource provide, where bare entanglement is not enough and Bell nonlocality may not be accessible.

6 Read more

Channel steering

Channel steering

We have generalized the notion of quantum steering from property of quantum states to property of quantum channels. We have discussed differences and similarities between the case of states and the case of channels, fo- cusing in particular on the issue of whether it makes sense to say that channel steering rules out the possibil- ity of hidden channels, rather than the possibility of an incoherent extension. We also discussed in detail how the notion for incoherence of extensions that we have adopted is well motivated operationally, since it com- prises the most general LOCC implementation of a chan- nel extension. Quite importantly, we have shown both a qualitative and a quantitative connection between state steering and channel steering. On one hand, the Choi- Jamio lkowski isomorphism allows us to map the study of channel steerability to the study of state steerability, leveraging known results in a new context. On the other hand, we have shown how tools developed to quantify state steering can be readily adopted to quantify chan- nel steering.

8 Read more

Necessary and sufficient quantum information characterization of Einstein-Podolsky-Rosen steering

Necessary and sufficient quantum information characterization of Einstein-Podolsky-Rosen steering

Entanglement is a property of distributed quantum systems that does not have a classical counterpart and challenges our everyday-life intuition about the physi- cal world [1]. It also is the key element in many quan- tum information processing tasks [2]. The strongest fea- ture exhibited by entangled systems is non-locality [3]. A weaker feature related to entanglement is steering : roughly speaking, in quantum steering one party can in- duce very different ensembles for the local state of the other party, beyond what is possible based only on a con- ceivable classical knowledge about the other party’s “hid- den state” [4, 5]. Steering embodies the “spooky action at a distance”—in the words of Einstein [6]—identified by Schroedinger [7], scrutinized by Einstein, Podolsky, and Rosen [8], and formally put on sound ground in [4, 5]. Not all entangled states are steerable, and not all steerable states exhibit nonlocality [4, 5], but states that exhibit steering allow for the verification of their entanglement in a semi-device independent way: there is no need to trust the devices used by the steering party [4, 5, 9]. Besides its foundational interest, steering is interesting in practice in bipartite tasks, like quantum key distribu- tion (QKD) [10], where it is convenient or appropriate to trust the devices of one of two parties, but not neces- sarily of the other one. For example, by exploiting steer- ing, key rates unachievable in a fully device-independent approach [11] are possible, still assuming less about the devices than in a standard QKD approach [12]. For these reasons, steering has recently attracted significant in- terest, both theoretically and experimentally [13–30], mostly directed to the verification of steering. Nonethe- less, an answer to the question “What is steering useful for?” can arguably be considered limited [9, 12]. Further-

6 Read more

Study of model predictive control for path-following autonomous ground vehicle control under crosswind effect

Study of model predictive control for path-following autonomous ground vehicle control under crosswind effect

2.1. Bicycle Model. Figure 1 shows a well-known vehicle model, which is a single-track model based on the simplifica- tion that the right and left wheels are lumped in a single wheel at the front and rear axles. The simplified vehicle model used in this paper illustrates the motion movement and dynamics concerning the car vehicle subject to the longitudinal, lateral, yaw, roll, and rotational dynamics of the front and rear wheel motion, represented as 6DoF. The longitudinal, lateral, and yaw dynamics effects are shown in Figure 1(b) as a top view of the car vehicle, and in Figure 1(a), the roll dynamics effect is explained with the nomenclature for a front view of the vehicle. In this paper, the nonlinear vehicle was linearized based on the assumption that sin 𝜃 = 0 and cos 𝜃 = 1 for both steering angles, the vehicle side slip angle, and the roll angle. We also assumed that the whole vehicle mass is sprung, which is ignoring the suspension and wheel weights for unsprung mass. This linearized model still behaves and represents the actual nonlinear vehicle model at certain operating points of the region. The details of the mathematical calculation for the vehicle model are presented in Chen and Peng [22] for further knowledge.

19 Read more

Steering system and suspension design for 2005 formula SAE-A car

Steering system and suspension design for 2005 formula SAE-A car

The first general design concept of the uprights consisted of a circular section with machined inside diameters to suit the wheel bearings. Two parts of “C” channel with appropriate manufactured end configuration for the wishbones assembly are to be welded on top and bottom of the circular part. The steering arm, and brake calliper mounting bracket is then welded on the upright. This concept is illustrated in Figure 33. The front upright provides a zero kingpin inclination and an adjustable zero or three degrees caster.

133 Read more

Design and Analysis of Suspension and Steering system along with the Wheel Assembly of a BAJA ATV

Design and Analysis of Suspension and Steering system along with the Wheel Assembly of a BAJA ATV

The steering ratio of 4:1 is achieved which means for every 4 degree rotation of steering wheel tires will be turned by 1 degree.The rack travels 8.89cm(3.5in) from lock to look to make the wheel turn.The front wheels configuration has a 3.5° camber angle and an 11˚ caster angle. The caster tends to drive the wheels forward, which makes it easier to maintain the car in a straight direction, also the inclination of the knuckle helps to reduce the turning radius to 2.408m, as shown in Figure

12 Read more

WIRE STEERING

WIRE STEERING

The SBW system I build can be improved a lot, but the main problem seems to be with thechoice of controllers and motors. For a future project, given better equipment, this system couldbe implemented in a small model car and can be used for control theory demonstrations. Newcontrol systems, such as state-space controls, can be implemented to enhance the performance ofthe system.Although not in the near future, given enough resources, this system can be implemented in real road cars and perhaps be combined with regular steering to take advantage of the safety benefits ofa steer-by-wire system.

11 Read more

An Overview on Future Electric Steering System: A Project Approach

An Overview on Future Electric Steering System: A Project Approach

full time electric power steering in regular production car, Acura NSX. This is an exotic sports car, competing in the market with Ferrari and Porsche; later this, a small European market economy car, the Fiat Punto will have Delphi‘s electrically boosted E-STEER as standard equipment. Delphi is busily marketing their electric power steering system to the world’s automotive design engineers, and it is expected to show upon several domestic cars in just a few years. There are lots of advantages to using an electric motor to provide steering boost, and many automotive engineers believe we now are seeing the last generation of hydraulic power steering. With a large change just around corner, a look at how electric power steering works imperative.

8 Read more

The Development Of Directional Control And Wheel Synchronization Od Vehicle Steering By Wire (VSBW) System By Implementing Fuzzy PID Controller (FPC)

The Development Of Directional Control And Wheel Synchronization Od Vehicle Steering By Wire (VSBW) System By Implementing Fuzzy PID Controller (FPC)

VSBW system expected not only implement same function as conventional mechanical coupling steering system, but it expected to provide advanced steering function. The front wheel needs to follow the input from the driver precisely. But in the real situation, the vehicle SBW system is faced many disturbances such as uneven condition of the road and parameter uncertainties of the system. Therefore, a more robust control system for VSBW system need to be develop.

24 Read more

Model of conflict management

Model of conflict management

According to Shelton & Darling (2004), there is a new management skill to deal with conflict namely quantum skills. Theses management skills are more appropriate for the contemporary organization and are derived from the field of quantum physics. There are total seven quantum skills: quantum seeing, quantum thinking, quantum feeling, quantum knowing, quantum acting, quantum trusting and quantum being.

14 Read more

Implementation of Thumb Controlled Braking and Acceleration in a Gearless Car for Physically Challenged Persons

Implementation of Thumb Controlled Braking and Acceleration in a Gearless Car for Physically Challenged Persons

With the same criteria using power steering, the acceleration and brake principles can be brought up and is modified into a button like structureand are embedded into the steering wheel. These buttons actuates the process according to the pressure given by the thumb finger of the user while holding the steering.There is a power provided from the battery /gen set to actuate the electrical components. Electromagnetic braking mechanism is preferred here that uses magnetic force of attraction to engage the brake. For a gradual increase/decrease the speed and brake, variable resistor is used which is connected to the bottom of the push button. The electromagnetic brakes can be used by controlling the current supplied to produce magnetic flux.

6 Read more

Design and analysis a lightweight knuckle for improving the formula student racing car

Design and analysis a lightweight knuckle for improving the formula student racing car

Automobiles knuckle is a part of vehicle suspension system and it is an important component as it carries varies type of load such as longitudinal, vertical and torque load. It is connected to the part of suspension and steering systems . It is used for adjusting the direction of a rotation through its attachment to the wheel. The automobile knuckle has a direct impact on the performance of the vehicle ride, steer ability and durability since this part link to the steering and suspension systems of the vehicle.

24 Read more

Steering Control For Bicycle

Steering Control For Bicycle

Strict dynamic model of bicycle was proposed by R.S.Sharp in 1971. It is named Sharp model and many researches are based on this model. A problem of this model is that it is complicated and difficult to apply to a bicycle posture controller. However, assuming that a rider doesn't move upper body, dynamics of the bicycle is represented in equilibrium of gravity and centrifugal force. Centrifugal force is risen out from the running velocity and turning radius which is determined by steering angle. Therefore under these conditions, it is possible to stabilize bicycle position by controlling steering [2].

24 Read more

Design and manufacturing of an effective steering system for a formula student car

Design and manufacturing of an effective steering system for a formula student car

Forces and moments were calculated arising due to normal reaction at tire-road interface due to vertical load and aligning torque while steering the vehicle. The driver must apply an effort on the steering wheel to overcome the aligning torque.

6 Read more

Dynamical Characteristics of a Lateral Guided Robotic Vehicle with a Rear Wheel Steering Mechanism Controlled by SSM

Dynamical Characteristics of a Lateral Guided Robotic Vehicle with a Rear Wheel Steering Mechanism Controlled by SSM

For the experiment, a test course was built having a 0.02 m wide strip of white tape on a black road surface. The geometry of the test course was identical to that used in the simulation. The surface material was constructed using acrylic film. Comparison of the simulated and experimental results required the measurement of the locus of the actual robot. Experimental data were acquired using a ProReflex (Qualisys) three- dimensional motion capture system having a sampling rate of 240 per second and a measuring error within ±0.2s mm. This measurement system captures the three-dimensional position of two reflecting markers attached to centers of the front and rear axles, and the captured data is output to a text file. A constant pulse interval is applied to a motor-driving circuit to produce a constant force equivalent to in the simulation. In this experiment, the maximum speed of the vehicle was set to 2.2 m/sec, and the control program stores the steering angle and the control variables in the built-in RAM every 10 ms. After each experimental run, the data is uploaded to a personal computer.

6 Read more

Optimization Of Vehicle Steering Wheel In Active Steering System

Optimization Of Vehicle Steering Wheel In Active Steering System

After that moment, the steering wheel stuck with the car, with its most common shape, which is a circle, unchanged for more than a century now. As humanity crawls its way through the 21th century, the steering wheel is quickly leaving behind its established role of vehicle controller and becomes command hub for the entire vehicle.

24 Read more

Show all 6682 documents...