Assigning Values and States

Mapping Intimacies ◽

10.1093/oso/9780198714057.003.0005 ◽

2017 ◽

Author(s):

Richard Healey

Keyword(s):

Quantum State ◽

Density Operator ◽

Entangled State ◽

Physical Situation ◽

Born Rule ◽

Correct Assignment ◽

Significant Magnitude ◽

Good Advice ◽

Empirical Significance ◽

Important Idea

If a quantum state is prescriptive then what state should an agent assign, what expectations does this justify, and what are the grounds for those expectations? I address these questions and introduce a third important idea—decoherence. A subsystem of a system assigned an entangled state may be assigned a mixed state represented by a density operator. Quantum state assignment is an objective matter, but the correct assignment must be relativized to the physical situation of an actual or hypothetical agent for whom its prescription offers good advice, since differently situated agents have access to different information. However this situation is described, it is true, empirically significant magnitude claims that make the description correct, while others provide the objective grounds for the agent’s expectations. Quantum models of environmental decoherence certify the empirical significance of these magnitude claims while also licensing application of the Born rule to others without mentioning measurement.

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Probability and Explanation

10.1093/oso/9780198714057.003.0009 ◽

2017 ◽

Author(s):

Richard Healey

Keyword(s):

Quantum Theory ◽

Quantum State ◽

Causal Explanation ◽

Born Rule ◽

Correct Application

We can use quantum theory to explain an enormous variety of phenomena by showing why they were to be expected and what they depend on. These explanations of probabilistic phenomena involve applications of the Born rule: to accept quantum theory is to let relevant Born probabilities guide one’s credences about presently inaccessible events. We use quantum theory to explain a probabilistic phenomenon by showing how its probabilities follow from a correct application of the Born rule, thereby exhibiting the phenomenon’s dependence on the quantum state to be assigned in circumstances of that type. This is not a causal explanation since a probabilistic phenomenon is not constituted by events that may manifest it: but each of those events does depend causally on events that actually occur in those circumstances. Born probabilities are objective and sui generis, but not all Born probabilities are chances.

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Entanglement

10.1093/oso/9780198714057.003.0003 ◽

2017 ◽

Author(s):

Richard Healey

Keyword(s):

Quantum Theory ◽

Quantum State ◽

Physical Condition ◽

Physical System ◽

Polarization State ◽

Quantum Systems ◽

Ghz State ◽

Mathematical Representation ◽

Entangled State ◽

Physical Relation

Often a pair of quantum systems may be represented mathematically (by a vector) in a way each system alone cannot: the mathematical representation of the pair is said to be non-separable: Schrödinger called this feature of quantum theory entanglement. It would reflect a physical relation between a pair of systems only if a system’s mathematical representation were to describe its physical condition. Einstein and colleagues used an entangled state to argue that its quantum state does not completely describe the physical condition of a system to which it is assigned. A single physical system may be assigned a non-separable quantum state, as may a large number of systems, including electrons, photons, and ions. The GHZ state is an example of an entangled polarization state that may be assigned to three photons.

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Time fractional evolution of a single quantum state and entangled state

Chaos Solitons & Fractals ◽

10.1016/j.chaos.2021.110930 ◽

2021 ◽

Vol 147 ◽

pp. 110930

Author(s):

Chuanjin Zu ◽

Yanming Gao ◽

Xiangyang Yu

Keyword(s):

Quantum State ◽

Entangled State ◽

Single Quantum

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MULTIPARTY REMOTELY PREPARING MULTIPARTITE EQUATORIAL ENTANGLED STATES IN HIGH DIMENSIONS

International Journal of Quantum Information ◽

10.1142/s0219749911008088 ◽

2011 ◽

Vol 09 (06) ◽

pp. 1437-1448

Author(s):

YI-BAO LI ◽

KUI HOU ◽

SHOU-HUA SHI

Keyword(s):

Quantum State ◽

Quantum Channel ◽

Success Probability ◽

Quantum States ◽

Remote State Preparation ◽

Entangled States ◽

Entangled State ◽

High Dimensions ◽

Original State ◽

State Preparation

We propose two kinds of schemes for multiparty remote state preparation (MRSP) of the multiparticle d-dimensional equatorial quantum states by using partial entangled state as the quantum channel. Unlike more remote state preparation scheme which only one sender knows the original state to be remotely prepared, the quantum state is shared by two-party or multiparty in this scheme. We show that if and only if all the senders agree to collaborate with each other, the receiver can recover the original state with certain probability. It is found that the total success probability of MRSP is only by means of the smaller coefficients of the quantum channel and the dimension d.

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INFLUENCE OF INTRINSIC DECOHERENCE ON THE ENTANGLEMENT BETWEEN TWO ATOMS IN TAVIS–CUMMINGS MODEL

International Journal of Quantum Information ◽

10.1142/s0219749908003335 ◽

2008 ◽

Vol 06 (01) ◽

pp. 167-179

Author(s):

CHUAN-JIA SHAN ◽

WEI-WEN CHENG ◽

TANG-KUN LIU ◽

YAN-XIA HUANG ◽

HONG LI ◽

...

Keyword(s):

Strong Coupling ◽

Quantum State ◽

Dipole Interaction ◽

Entangled State ◽

Entanglement Dynamics ◽

Initial State ◽

Intrinsic Decoherence ◽

Dipole Coupling ◽

Fock State

Considering the dipole–dipole coupling intensity between two atoms and the field in the Fock state, the entanglement dynamics between two atoms that are initially entangled in the Tavis–Cummings model with intrinsic decoherence have been investigated. The two-atom entanglement appears with periodicity without considering intrinsic decoherence. However, the intrinsic decoherence causes the decay of entanglement between two atoms, with the decrease of the intrinsic decoherence coefficient, the entanglement will quickly become a constant value, which is affected by the two-atom initial state, the dipole–dipole coupling intensity and the field in the Fock state. Meanwhile, the two-atom quantum state will stay forever in the maximal entangled state when the initial state is proper, even in the presence of intrinsic decoherence. Furthermore, the two atoms can generate maximal entangled state even if they are initially separated by adjusting the dipole–dipole interaction, the strong coupling can improve the value of entanglement.

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Deterministic quantum teleportation through fiber channels

Science Advances ◽

10.1126/sciadv.aas9401 ◽

2018 ◽

Vol 4 (10) ◽

pp. eaas9401 ◽

Cited By ~ 21

Author(s):

Meiru Huo ◽

Jiliang Qin ◽

Jialin Cheng ◽

Zhihui Yan ◽

Zhongzhong Qin ◽

...

Keyword(s):

Communication Networks ◽

Quantum State ◽

Optical Fibers ◽

Quantum Teleportation ◽

Continuous Variable ◽

Entangled State ◽

Optical Modes ◽

Unknown Quantum State ◽

Einstein Podolsky Rosen ◽

Fiber Channels

Quantum teleportation, which is the transfer of an unknown quantum state from one station to another over a certain distance with the help of nonlocal entanglement shared by a sender and a receiver, has been widely used as a fundamental element in quantum communication and quantum computation. Optical fibers are crucial information channels, but teleportation of continuous variable optical modes through fibers has not been realized so far. Here, we experimentally demonstrate deterministic quantum teleportation of an optical coherent state through fiber channels. Two sub-modes of an Einstein-Podolsky-Rosen entangled state are distributed to a sender and a receiver through a 3.0-km fiber, which acts as a quantum resource. The deterministic teleportation of optical modes over a fiber channel of 6.0 km is realized. A fidelity of 0.62 ± 0.03 is achieved for the retrieved quantum state, which breaks through the classical limit of1/2. Our work provides a feasible scheme to implement deterministic quantum teleportation in communication networks.

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FIELD PURIFICATION OF A GENERAL THREE-LEVEL SYSTEM INTERACTING WITH RADIATION

Modern Physics Letters B ◽

10.1142/s0217984903005135 ◽

2003 ◽

Vol 17 (07) ◽

pp. 253-262 ◽

Cited By ~ 5

Author(s):

MAHMOUD ABDEL-ATY

Keyword(s):

Exact Solution ◽

Electromagnetic Field ◽

Density Operator ◽

Photon Number ◽

Entangled State ◽

Level System ◽

Level Atom ◽

Coherent Field ◽

Field Purity ◽

Intensity Dependent Coupling

In this essay we introduce a new Hamiltonian which represents the interaction between a three-level atom and a single electromagnetic field including arbitrary forms of nonlinearities of both the field and the intensity-dependent coupling. We derive an exact solution for the density operator of the system by means of which we study the field purity for the entangled state of the system. Also, the influences of the nonlinearities on the field purity and mean photon number are examined. Under the condition of an initial coherent field, the field purity shows the collapse-revival phenomenon. It is found that features of these phenomenon are sensitive to the changes of different kinds of the nonlinearities.

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