Undoing Quantum Measurement: Novel Twists to the Physical Account of Time (original) (raw)

Undoing quantum measurement must violate either determinism, Lorentz invariance or time-symmetry

The peaceful coexistence between quantum mechanics and special relativity is maintained due to the unobservability of hidden variables, and hence the intrinsic unobservability of quantum non-locality in real time. I prove that if time-reversing quantum measurement is possible, this coexistence breaks down. Either Lorentz invariance or time-symmetry must be visibly violated, the more radical option being the inexistence of hidden variables.

Time-Reversed Epr and the Choice of Histories in Quantum Mechanics

The Physics of Communication, 2003

When a single photon is split by a beam splitter, its two "halves" can entangle two distant atoms into an EPR pair. We discuss a time-reversed analogue of this experiment where two distant sources cooperate so as to emit a single photon. The two "half photons," having interacted with two atoms, can entangle these atoms into an EPR pair once they are detected as a single photon. Entanglement occurs by creating indistinguishabilility between the two mutually exclusive histories of the photon.

The Backwards-Time Interpretation of Quantum Mechanics - Revisited With Experiment

Eprint Arxiv Quant Ph 0008036, 2000

The classic paper of Clauser et al proved that Bell's Theorem experiments rule out all theories of physics which assume locality, time-forwards causality and the existence of an objective real world. The Backwards-Time Interpretation (BTI) tries to recover realism and locality by permitting backwards time causality. BTI should permit dramatic simplification of the assumptions or axioms of physics, but requires new work in fundamental mathematics, such as new tools for the "closure of turbulence," the derivation of statistics generated by ODE or PDE. Recent events like the Delayed Choice Quantum Eraser experiment of Kim, Shih et al have increased mainstream interest in the possibility of backwards causality. The Backwards Time Quantum Teleportation (BTQT) experiment will take this further. True backwards time communication channels (BTCC) are absolutely impossible in most formulations of quantum theory but only almost impossible in the BTI formulation. This paper discusses BTQT, the issue of backwards causality in different versions of quantum theory and new mathematical developments. Predictions of a common toy field theory (real ϕ 3 QFT) are reproduced by the corresponding PDE model combined with a new model of the micro/macro interface (2M/M).

Partial Measurements and the Realization of Quantum-Mechanical Counterfactuals

Foundations of Physics, 2011

We propose partial measurements as a conceptual tool to understand how to operate with counterfactual claims in quantum physics. Indeed, unlike standard von Neumann measurements, partial measurements can be reversed probabilistically. We first analyze the consequences of this rather unusual feature for the principle of superposition, for the complementarity principle, and for the issue of hidden variables. Then we move on to exploring non-local contexts, by reformulating the EPR paradox, the quantum teleportation experiment, and the entanglement-swapping protocol for the situation in which one uses partial measurements followed by their stochastic reversal. This leads to a number of counter-intuitive results, which are shown to be resolved if we give up the idea of attributing reality to the wavefunction of a single quantum system.

Two time solution to quantum measurement paradoxes

arXiv: Quantum Physics, 2017

It is hypothesized that the Langevin time of stochastic quantum quantization is a physical time over which quantum fields at all values of space and coordinate time fluctuate. The average over paths becomes a time average as opposed to an ensemble average. It is further hypothesized that the Langevin time also paces the motion of particles through coordinate time and is equal to the coordinate time of the present hypersurface in the frame of the Hubble expansion. Despite having a preferred frame, special relativity continues to hold in this formulation as a dynamical symmetry due to the presumed Lorentz invariance of interactions. The measurement process becomes an integral part of the theory and is realized as a process of spontaneous symmetry breaking. The continuously fluctuating history of fields, characteristic of having two times, and the switch from ensemble averages to time averages allows for logical and straightforward explanations of many quantum measurement paradoxes. Th...

Time’s Direction and Orthodox Quantum Mechanics: Time Symmetry and Measurement

Journal for General Philosophy of Science

It has been argued that measurement-induced collapses in Orthodox Quantum Mechanics generates an intrinsic (or built-in) quantum arrow of time. In this paper, I critically assess this proposal. I begin by distinguishing between an intrinsic and nonintrinsic arrow of time. After presenting the proposal of a collapse-based arrow of time in some detail, I argue, first, that any quantum arrow of time in Orthodox Quantum Mechanics is non-intrinsic since it depends on external information about the measurement context, and second, that it cannot be global, but just local. I complement these arguments by assessing some criticisms and considerations about the implementation of time reversal in contexts wherein measurement-induced collapses work. I conclude that the quantum arrow of time delivered by Orthodox Quantum Mechanics is much weaker than usually thought.