@article {3313, title = {A Watermark for Large Language Models}, year = {2023}, month = {6/6/2023}, abstract = {

Potential harms of large language models can be mitigated by watermarking model output, i.e., embedding signals into generated text that are invisible to humans but algorithmically detectable from a short span of tokens. We propose a watermarking framework for proprietary language models. The watermark can be embedded with negligible impact on text quality, and can be detected using an efficient open-source algorithm without access to the language model API or parameters. The watermark works by selecting a randomized set of \"green\" tokens before a word is generated, and then softly promoting use of green tokens during sampling. We propose a statistical test for detecting the watermark with interpretable p-values, and derive an information-theoretic framework for analyzing the sensitivity of the watermark. We test the watermark using a multi-billion parameter model from the Open Pretrained Transformer (OPT) family, and discuss robustness and security.

}, url = {https://arxiv.org/abs/2301.10226}, author = {John Kirchenbauer and Jonas Geiping and Yuxin Wen and Jonathan Katz and Ian Miers and Tom Goldstein} } @article {3289, title = {What happens to entropy production when conserved quantities fail to commute with each other}, year = {2023}, month = {5/24/2023}, abstract = {

We extend entropy production to a deeply quantum regime involving noncommuting conserved quantities. Consider a unitary transporting conserved quantities (\"charges\") between two systems initialized in thermal states. Three common formulae model the entropy produced. They respectively cast entropy as an extensive thermodynamic variable, as an information-theoretic uncertainty measure, and as a quantifier of irreversibility. Often, the charges are assumed to commute with each other (e.g., energy and particle number). Yet quantum charges can fail to commute. Noncommutation invites generalizations, which we posit and justify, of the three formulae. Charges\&$\#$39; noncommutation, we find, breaks the formulae\&$\#$39;s equivalence. Furthermore, different formulae quantify different physical effects of charges\&$\#$39; noncommutation on entropy production. For instance, entropy production can signal contextuality - true nonclassicality - by becoming nonreal. This work opens up stochastic thermodynamics to noncommuting - and so particularly quantum - charges.

}, url = {https://arxiv.org/abs/2305.15480}, author = {Twesh Upadhyaya and William F. Braasch, Jr. and Gabriel T. Landi and Nicole Yunger Halpern} } @article {3043, title = {Where we are with quantum}, journal = {Nature Physics}, year = {2022}, month = {4/28/2022}, abstract = {

A theoretical analysis shows how a person\’s location in space could be verified by the transmission of single photons. A vital application of quantum networks may be within reach.

}, issn = {1745-2473}, doi = {https://doi.org/10.1038/s41567-022-01597-w}, author = {Yusuf Alnawakhtha and Carl Miller} } @article {2097, title = {Why Bohr was (Mostly) Right}, year = {2017}, month = {2017/11/05}, abstract = {

After a discussion of the Frauchiger-Renner argument that no \“singleworld\” interpretation of quantum mechanics can be self-consistent, I propose a \“Bohrian\” alternative to many-worlds or QBism as the rational option.

}, url = {https://arxiv.org/abs/1711.01604}, author = {Jeffrey Bub} } @article {1823, title = {Wannier functions using a discrete variable representation for optical lattices}, journal = {Physical Review A}, volume = {94}, year = {2016}, month = {2016/09/07}, pages = {033606}, abstract = {

We propose a numerical method using the discrete variable representation (DVR) for constructing real-valued Wannier functions localized in a unit cell for both symmetric and asymmetric periodic potentials. We apply these results to finding Wannier functions for ultracold atoms trapped in laser-generated optical lattices. Following S. Kivelson [Phys. Rev. B26, 4269 (1982)], for a symmetric lattice with inversion symmetry, we construct Wannier functions as eigenstates of the position operators\ x,y, and\ z\ restricted to single-particle Bloch functions belonging to one or more bands. To ensure that the Wannier functions are real-valued, we numerically obtain the band structure and real-valued eigenstates using a uniform Fourier grid DVR. We then show, by a comparison of tunneling energies, that the Wannier functions are accurate for both inversion-symmetric and asymmetric potentials to better than 10 significant digits when using double-precision arithmetic. The calculations are performed for an optical lattice with double-wells per unit cell with tunable asymmetry along the\ x\ axis and a single sinusoidal potential along the perpendicular directions. Localized functions at the two potential minima within each unit cell are similarly constructed, but using a superposition of single-particle solutions from the two lowest bands. We finally use these localized basis functions to determine the two-body interaction energies in the Bose-Hubbard model and show the dependence of these energies on lattice asymmetry.

}, doi = {http://dx.doi.org/10.1103/PhysRevA.94.033606}, url = {http://journals.aps.org/pra/abstract/10.1103/PhysRevA.94.033606}, author = {Saurabh Paul and Eite Tiesinga} } @article {1602, title = {Whose Information? Information About What?}, journal = {Quantum [Un]Speakables II: 50 Years of Bell{\textquoteright}s Theorem}, year = {2016}, month = {2016/01/01}, author = {Jeffrey Bub and Anton Zeilinger and Reinhold Bertlmann} } @article {2630, title = {When the asymptotic limit offers no advantage in the local-operations-and-classical-communication paradigm}, journal = {Phys. Rev. A }, volume = {89}, year = {2014}, month = {5/9/2014}, abstract = {

We consider bipartite LOCC, the class of operations implementable by local quantum operations and classical communication between two parties. Surprisingly, there are operations that can be approximated to arbitrary precision but are impossible to implement exactly if only a finite number of messages are exchanged. This significantly complicates the analysis of what can or cannot be approximated with LOCC. Toward alleviating this problem, we exhibit two scenarios in which allowing vanishing error does not help. The first scenario is implementation of projective measurements with product measurement operators. The second scenario is the discrimination of unextendable product bases on two three-dimensional systems.

}, doi = {https://doi.org/10.1103/PhysRevA.89.052310}, author = {Honghao Fu and Debbie Leung and Laura Mancinska} } @article {1319, title = {Why the Tsirelson bound?}, journal = {The Probable and the Improbable: The Meaning and Role of Probability in Physics}, year = {2012}, month = {2012/08/18}, pages = {167-185}, abstract = { Wheeler{\textquoteright}s question {\textquoteright}why the quantum{\textquoteright} has two aspects: why is the world quantum and not classical, and why is it quantum rather than superquantum, i.e., why the Tsirelson bound for quantum correlations? I discuss a remarkable answer to this question proposed by Pawlowski et al (2009), who provide an information-theoretic derivation of the Tsirelson bound from a principle they call {\textquoteright}information causality.{\textquoteright} }, doi = {10.1007/978-3-642-21329-8_11}, url = {http://arxiv.org/abs/1208.3744v1}, author = {Jeffrey Bub} } @article {1357, title = {Wigner crystals of ions as quantum hard drives}, journal = {Physical Review A}, volume = {78}, year = {2008}, month = {2008/12/18}, abstract = {Atomic systems in regular lattices are intriguing systems for implementing ideas in quantum simulation and information processing. Focusing on laser cooled ions forming Wigner crystals in Penning traps, we find a robust and simple approach to engineering non-trivial 2-body interactions sufficient for universal quantum computation. We then consider extensions of our approach to the fast generation of large cluster states, and a non-local architecture using an asymmetric entanglement generation procedure between a Penning trap system and well-established linear Paul trap designs. }, doi = {10.1103/PhysRevA.78.062331}, url = {http://arxiv.org/abs/0706.1951v1}, author = {J. M. Taylor and T. Calarco} } @article {1241, title = {Weak Fourier-Schur sampling, the hidden subgroup problem, and the quantum collision problem }, year = {2006}, month = {2006/09/14}, abstract = { Schur duality decomposes many copies of a quantum state into subspaces labeled by partitions, a decomposition with applications throughout quantum information theory. Here we consider applying Schur duality to the problem of distinguishing coset states in the standard approach to the hidden subgroup problem. We observe that simply measuring the partition (a procedure we call weak Schur sampling) provides very little information about the hidden subgroup. Furthermore, we show that under quite general assumptions, even a combination of weak Fourier sampling and weak Schur sampling fails to identify the hidden subgroup. We also prove tight bounds on how many coset states are required to solve the hidden subgroup problem by weak Schur sampling, and we relate this question to a quantum version of the collision problem. }, doi = {10.1007/978-3-540-70918-3_51}, url = {http://arxiv.org/abs/quant-ph/0609110v1}, author = {Andrew M. Childs and Aram W. Harrow and Pawel Wocjan} } @article {1311, title = {Why the quantum?}, year = {2004}, month = {2004/02/20}, abstract = { This paper is a commentary on the foundational significance of the Clifton-Bub-Halvorson theorem characterizing quantum theory in terms of three information-theoretic constraints (Foundations of Physics 33, 1561-1591 (2003); quant-ph/0211089). I argue that: (1) a quantum theory is best understood as a theory about the possibilities and impossibilities of information transfer, as opposed to a theory about the mechanics of nonclassical waves or particles, (2) given the information-theoretic constraints, any mechanical theory of quantum phenomena that includes an account of the measuring instruments that reveal these phenomena must be empirically equivalent to a quantum theory, and (3) assuming the information-theoretic constraints are in fact satisfied in our world, no mechanical theory of quantum phenomena that includes an account of measurement interactions can be acceptable, and the appropriate aim of physics at the fundamental level then becomes the representation and manipulation of information. }, url = {http://arxiv.org/abs/quant-ph/0402149v1}, author = {Jeffrey Bub} }