Significant-Loophole-Free Test of Local Realism with Entangled Photons

Giustina, Marissa; Versteegh, Marijn A. M.; Wengerowsky, Sören; Handsteiner, Johannes; Hochrainer, Armin; Phelan, K.; Steinlechner, Fabian; Kofer, J.; Larson, J-A.; Abelan, C.; Amaya, Waldimar; Pruneri, Valerio; Mitchel, M. W. M.; Beyer, J.; Gerrits, Thomas; Lita, Adriana E.; Shalm, Lynden K.; Nam, Sae Woo; Scheidl, Thomas; Ursin, Rupert; Wittmann, Bernhard; Zeilinger, Anton

doi:10.1364/cleo_qels.2016.fw4c.3

Cited by 47 publications

(59 citation statements)

References 11 publications

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“…This coupling has been used to demonstrate entanglement between two NV centers located 25 nm apart [19]. If each NV were to in turn interact with a small (2)(3)(4) number of local nuclear spins, this would already provide access to a relatively large subspace for performing quantum algorithms. This approach also cannot scale indefinitely; however, this modest improvement would push the system over an important size threshold -namely, that required for fault-tolerant quantum computing.…”

Section: Scaling Quantum Algorithmsmentioning

confidence: 99%

“…At present, while there have been a number of remarkable achievements in the field, ranging from prototype quantum repeaters demonstrating loopholefree violations of Bell's inequality [2][3][4] to small quantum computers with error-correctionextended lifetimes [5], the scale of the systems built remains small, limited to a handful of qubits. Larger systems have been proposed and preliminary devices built, but major challenges remain, including error and crosstalk suppression [6,7].…”

Section: Introductionmentioning

confidence: 99%

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Super-Resolution Localization and Readout of Individual Solid State Qubits

Bersin

Walsh

Mouradian

et al. 2018

Conference on Lasers and Electro-Optics

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A central goal in quantum information science is to establish entanglement across multiple quantum memories in a manner that allows individual control and readout of each constituent qubit. In the area of solid state quantum optics, a leading system is the negatively charged nitrogen vacancy center in diamond, which allows access to a spin center that can be entangled to multiple nuclear spins. Scaling these systems will require the entanglement of multiple NV centers, together with their nuclear spins, in a manner that allows for individual control and readout. Here we demonstrate a technique that allows us to prepare and measure individual centers within an ensemble, well below the diffraction limit. The technique relies on optical addressing of spin-dependent transitions, and makes use of the built-in inhomogeneous distribution of emitters resulting from strain splitting to measure individual spins in a manner that is non-destructive to the quantum state of other nearby centers. We demonstrate the ability to resolve individual NV centers with subnanometer spatial resolution. Furthermore, we demonstrate crosstalk-free individual readout of spin populations within a diffraction limited spot by performing resonant readout of one NV during a spectroscopic sequence of another. This method opens the door to multi-qubit coupled spin systems in solids, with individual spin manipulation and readout.

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Section: Scaling Quantum Algorithmsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Super-Resolution Localization and Readout of Individual Solid State Qubits

Bersin

Walsh

Mouradian

et al. 2018

Conference on Lasers and Electro-Optics

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“…In the context of quantum theory, an objective view of the chances would start with ("bare") quantum theory to generate the conditional chances, while an epistemic view would take the experimental tests of Bell inequality violations as evidence for the correct chances. The loophole-free tests (Giustina et al 2015) should be enough to convince most that the chance of violating the Bell inequalities is approximately one, so we end up with practically indistinguishable chances as when we start from quantum theory. In either case, causation is unnecessary for getting at the chances predicted by quantum theory, and so something broader than causal relationships may be used in CDT.…”

Section: Cdt and Causationmentioning

confidence: 99%

Do the EPR correlations pose a problem for causal decision theory?

2017

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We argue that Causal Decision Theory (CDT) is no worse off than Evidential Decision Theory (EDT) in handling entanglement, regardless of one's preferred interpretation of quantum mechanics. In recent works, Ahmed (2014) and Ahmed and Caulton (2014) have claimed the opposite; we argue that they are mistaken. Bell-type experiments are not instances of Newcomb problems, so CDT and EDT do not diverge in their recommendations. We highlight the fact that a Causal Decision Theorist should take all lawlike correlations into account, including potentially acausal entanglement correlations. This paper also provides a brief introduction to CDT with a motivating "small" Newcomb problem. The main point of our argument is that quantum theory does not provide grounds for favouring EDT over CDT.

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“…This is related to Wheeler's delayed choice gedanken experiment, [20] and has been experimentally demonstrated. [4] [5] It is important to note that this is not a quirk of a particular experiment, but a fundamental principle in quantum systems that is true in general situations. Whenever we perform a projective measurement on a system in a quantum superposition, we get a definite outcome, and the entire history since the system became superposed falls into place when the measurement outcome is obtained.…”

Section: Retroactive Event Determinationmentioning

confidence: 99%

“…A realist will wonder how one can discuss "histories" of physical things in a mathematically abstract space. Yet many experimental results in modern physics support this view: instantaneous correlation at a distance [4]; a delayed choice that retroactively determines a prior state of a system [5] [6]; erasing the "fact" that a measurement has been made on a system [7]; separating the properties of a particle from the particle itself [8]. As Mermin alluded to earlier, the 'real' entities are the relationships between things, but the things themselves do not have independent existence.…”

Section: Introductionmentioning

confidence: 99%

Guiding quantum histories with intermediate decomposition of the identity

Nelson-Isaacs¹

2017

AIP Conference Proceedings

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Abstract. The effect of a carefully chosen measurement action is proposed to be able to influence the probability distribution of future outcomes. Using the consistent histories formalism, we may calculate the overlap between a current measurement action and an array of possible future states. We propose an interpretation of the mathematics in which a current measurement action reaches recursively into future states and returns a probability. Using intermediate decomposition of a quantum history, we decompose a state at intermediate times into a complete set of states, using a grouping which distinguishes particular outcomes. The "meaning" of the grouping is defined rigorously, and it is shown that under certain minimal assumptions a 'meaningful grouping' will always increase the likelihood of a particular outcome. This is labeled "meaningful history selection." Grouping histories is not a physical process, but rather an information theoretic one that occurs during the measurement process. The model is consistent with the standard Von Neumann measurement process under normal conditions, but leads to a proposed small deviation in the presence of a conscious observer that naturally accommodates the experimental evidence of certain psi phenomena. It is proposed that the effect of a conscious observer acting on a system is to group the histories in a distinguishable way, thereby minimizing the entropy increase of the system upon measurement. Compatibility with various models of quantum theory are discussed.

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Significant-Loophole-Free Test of Local Realism with Entangled Photons

Cited by 47 publications

References 11 publications

Super-Resolution Localization and Readout of Individual Solid State Qubits

Super-Resolution Localization and Readout of Individual Solid State Qubits

Do the EPR correlations pose a problem for causal decision theory?

Guiding quantum histories with intermediate decomposition of the identity

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