## Publications

139 results found

Rudolph T, Pan J-W, 2001, A simple gate for linear optics quantum computing, *Arxiv.org*, Pages: 1-1

RUDOLPH T, 2000, Better schemes for quantum interrogation in lossy experiments, Vol: 85, Pages: 2925-2928

BEN-ARYEH Y, FREEDHOFF H, RUDOLPH T, 1999, Photon correlations in the fluorescence from a bichromatically driven atom, Vol: 1, Pages: 624-630

Rudolph T, 1999, Quantum Information is physical too, *http://www.arxiv.org/abs/quant-ph/9904037*, Vol: x, Pages: x-x

FICEK Z, FREEDHOFF H, RUDOLPH T, 1999, Dressing dressed states, Vol: 87, Pages: 670-675

Rudolph T, 1999, Quantum Triangulation and Violation of Conservation of Trouble, *http://www.arxiv.org/abs/quant-ph/9902010*, Vol: x, Pages: x-x

FICEK Z, RUDOLPH T, 1999, Quantum interference in a driven two-level atom, Vol: 60, Pages: R4245-R4248

RUDOLPH T, FREEDHOFF H, FICEK Z, 1998, Shift of the subharmonic resonances and suppression of fluorescence in a two-level atom driven by a bichromatic field, Vol: 15, Pages: 2325-2330

RUDOLPH T, FICEK Z, 1998, Interference pattern with a dark center from two atoms driven by a coherent laser field, Vol: 58, Pages: 748-751

RUDOLPH T, FREEDHOFF H, FICEK Z, 1998, Multiphoton ac Stark effect in a bichromatically driven two-level atom, Vol: 58, Pages: 1296-1309

RUDOLPH T, FICEK Z, FREEDHOFF H, 1998, The multiphoton AC Stark effect, Vol: 147, Pages: 78-82

RUDOLPH T, FICEK Z, DALTON B, 1995, 2-ATOM RESONANCE FLUORESCENCE IN RUNNING-WAVE AND STANDING-WAVE LASER FIELDS, Vol: 52, Pages: 636-656

Rudolph T, Ontological Models for Quantum Mechanics and the Kochen-Specker theorem

Certain concrete "ontological models" for quantum mechanics (models in whichmeasurement outcomes are deterministic and quantum states are equivalent toclassical probability distributions over some space of `hidden variables') areexamined. The models are generalizations of Kochen and Specker's such model fora single 2-dimensional system - in particular a model for a three dimensionalquantum system is considered in detail. Unfortunately, it appears the models donot quite reproduce the quantum mechanical statistics. They do, however, comeclose to doing so, and in as much as they simply involve probabilitydistributions over the complex projective space they do reproduce pretty mucheverything else in quantum mechanics. The Kochen-Specker theorem is examined in the light of these models, and therather mild nature of the manifested contextuality is discussed.

Seis Y, Brown BJ, SÃ¸rensen AS, et al., Extending the memory times of trapped-ion qubits with error correction and global entangling operations

The technical demands to perform quantum error correction are considerable.The task requires the preparation of a many-body entangled state, together withthe ability to make parity measurements over subsets of the physical qubits ofthe system to detect errors. Here we propose two trapped-ion experiments torealise error-correcting codes of variable size to protect a single encodedqubit from dephasing errors. Novel to our schemes is the use of a globalentangling phase gate, which could be implemented in both Penning traps andPaul traps. We make use of this entangling operation to significantly reducethe experimental complexity of state preparation and syndrome measurements. Wealso show, in our second scheme, that storage times can be increased further byrepeatedly teleporting the logical information between two codes supported bythe same ion Coulomb crystal to learn information about the locations oferrors. We estimate that a logical qubit encoded in such a crystal willmaintain high coherence for times more than an order of magnitude longer thaneach physical qubit would.

Harrigan N, Rudolph T, Ontological models and the interpretation of contextuality

Studying the extent to which realism is compatible with quantum mechanicsteaches us something about the quantum mechanical universe, regardless of thevalidity of such realistic assumptions. It has also recently been appreciatedthat these kinds of studies are fruitful for questions relating to quantuminformation and computation. Motivated by this, we extend the ontological modelformalism for realistic theories to describe a set of theories emphasizing therole of measurement and preparation devices by introducing `hidden variables'to describe them. We illustrate both the ontological model formalism and ourgeneralization of it through a series of example models taken from theliterature. Our extension of the formalism allows us to quantitatively analyzethe meaning contextuality (a constraint on successful realistic theories),finding that - taken at face-value - it can be realized as a naturalinteraction between the configurations of a system and measurement device.However, we also describe a property that we call deficiency, which followsfrom contextuality, but does not admit such a natural interpretation. Looselyspeaking, deficiency breaks a symmetry between preparations and measurements inquantum mechanics. It is the property that the set of ontic states which asystem prepared in quantum state psi may actually be in, is strictly smallerthan the set of ontic states which would reveal the measurement outcome psiwith certainty.

Arndt M, Aspelmeyer M, Bernstein HJ, et al., Quantum Physics from A to Z

This is a collection of statements gathered on the occasion of the QuantumPhysics of Nature meeting in Vienna.

Ashoori E, Rudolph T, Commentary on Quantum-Inspired Information Retrieval

There have been suggestions within the Information Retrieval (IR) communitythat quantum mechanics (QM) can be used to help formalise the foundations ofIR. The invoked connection to QM is mathematical rather than physical. Theproposed ideas are concerned with information which is encoded, processed andaccessed in classical computers. However, some of the suggestions have beenthoroughly muddled with questions about applying techniques of quantuminformation theory in IR, and it is often unclear whether or not the suggestionis to perform actual quantum information processing on the information. Thispaper is an attempt to provide some conceptual clarity on the emerging issues.

Harrigan N, Rudolph T, Aaronson S, Representing probabilistic data via ontological models

Ontological models are attempts to quantitatively describe the results of aprobabilistic theory, such as Quantum Mechanics, in a framework exhibiting anexplicit realism-based underpinning. Unlike either the well knownquasi-probability representations, or the "r-p" vector formalism, these modelsare contextual and by definition only involve positive probabilitydistributions (and indicator functions). In this article we study how theontological model formalism can be used to describe arbitrary statistics of asystem subjected to a finite set of preparations and measurements. We presentthree models which can describe any such empirical data and then discuss how toturn an indeterministic model into a deterministic one. This raises the issueof how such models manifest contextuality, and we provide an explicit exampleto demonstrate this. In the second half of the paper we consider the issue offinding ontological models with as few ontic states as possible.

Jevtic S, Rudolph T, How Einstein and/or Schrödinger should have discovered Bell's Theorem in 1936, *JOSA B*, Vol: 32

We show how one can be led from considerations of quantum steering to Bell'stheorem. We begin with Einstein's demonstration that, assuming local realism,quantum states must be in a many-to-one ("incomplete") relationship with thereal physical states of the system. We then consider some simple constraintsthat local realism imposes on any such incomplete model of physical reality,and show they are not satisfiable. In particular, we present a very simpledemonstration for the absence of a local hidden variable incomplete descriptionof nature by steering to two ensembles, one of which contains a pair ofnon-orthogonal states. Historically this is not how Bell's theorem arose -there are slight and subtle differences in the arguments - but it could havebeen.

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