Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userA Stronger Theorem Against Macro-realism
68
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Macro-realism is the position that certain macroscopic observables must always possess definite values: e.g. the table is in some definite position, even if we dont know what that is precisely. The traditional understanding is that by assuming macro-realism one can derive the Leggett-Garg inequalities, which constrain the possible statistics from certain experiments. Since quantum experiments can violate the Leggett-Garg inequalities, this is taken to rule out the possibility of macro-realism in a quantum universe. However, recent analyses have exposed loopholes in the Leggett-Garg argument, which allow many types of macro-realism to be compatible with quantum theory and hence violation of the Leggett-Garg inequalities. This paper takes a different approach to ruling out macro-realism and the result is a no-go theorem for macro-realism in quantum theory that is stronger than the Leggett-Garg argument. This approach uses the framework of ontological models: an elegant way to reason about foundational issues in quantum theory which has successfully produced many other recent results, such as the PBR theorem.
rate research
Read More
We show how to apply the Leggett-Garg inequality to opto-electro-mechanical systems near their quantum ground state. We find that by using a dichotomic quantum non-demolition measurement (via, e.g., an additional circuit-QED measurement device) either on the cavity or on the nanomechanical system itself, the Leggett-Garg inequality is violated. We argue that only measurements on the mechanical system itself give a truly unambigous violation of the Leggett-Garg inequality for the mechanical system. In this case, a violation of the Leggett-Garg inequality indicates physics beyond that of macroscopic realism is occurring in the mechanical system. Finally, we discuss the difficulties in using unbound non-dichotomic observables with the Leggett-Garg inequality.
We construct quantifiable generalisations of Leggett-Garg tests for macro/ mesoscopic realism and noninvasive measurability that apply when not all outcomes of measurement can be identified as arising from one of two macroscopically distinguishable states. We show how quantum mechanics predicts a negation of the LG premises for proposals involving ideal-negative-result, weak and quantum non-demolition measurements on dynamical entangled systems, as might be realised with two-well Bose-Einstein condensates, path-entangled NOON states and atom interferometers.
I point out critical errors in the paper Bells Theorem Versus Local Realism in a Quaternionic Model of Physical Space by J. Christian, published in IEEE Access. Christians paper in fact contains several conflicting models. None of them form counterexamples to Bells theorem. Most of Christians paper is devoted to a model based on the detection loophole due to Pearle (1970).
Given a group $G$, we write $x^G$ for the conjugacy class of $G$ containing the element $x$. A famous theorem of B. H. Neumann states that if $G$ is a group in which all conjugacy classes are finite with bounded size, then the derived group $G$ is finite. We establish the following result. Let $n$ be a positive integer and $K$ a subgroup of a group $G$ such that $|x^G|leq n$ for each $xin K$. Let $H=langle K^Grangle$ be the normal closure of $K$. Then the order of the derived group $H$ is finite and $n$-bounded. Some corollaries of this result are also discussed.
We present a loophole-free violation of local realism using entangled photon pairs. We ensure that all relevant events in our Bell test are spacelike separated by placing the parties far enough apart and by using fast random number generators and high-speed polarization measurements. A high-quality polarization-entangled source of photons, combined with high-efficiency, low-noise, single-photon detectors, allows us to make measurements without requiring any fair-sampling assumptions. Using a hypothesis test, we compute p-values as small as $5.9times 10^{-9}$ for our Bell violation while maintaining the spacelike separation of our events. We estimate the degree to which a local realistic system could predict our measurement choices. Accounting for this predictability, our smallest adjusted p-value is $2.3 times 10^{-7}$. We therefore reject the hypothesis that local realism governs our experiment.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
