Hi all,
Tomorrow Eduardo González Sánchez will tell us about his master thesis on
"Extracting physical parameters from an environment using AI-agents". See
below for the abstract. We start at 3pm in zoom:
https://ethz.zoom.us/j/362994444.
Best,
-joe
Abstract: An important challenge for the automation of science is to
minimize the prior human knowledge built into the machine learning systems.
A step in this direction was done in Phys. Rev. Lett. 124, 010508 (2020)
where the relevant physical …
[View More]parameters were extracted from experimental
data without using prior knowledge about the specific physical system. Here,
we go one step further in minimizing prior knowledge: We do not consider
the experimental data as given but train AI agents that learn to perform
the experiments that provide the necessary data to extract the relevant
parameters. To do so, we combine in a modular architecture techniques from
reinforcement learning and deep learning. We demonstrate the working of our
architecture with some toy examples. Reading out the parameters for the
given examples is left for future work.
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Hi all,
Tomorrow Sebastian Stengele will present the results of his master thesis,
on "Superpositions of Spacetimes in the Low Velocity Limit". See below for
the abstract. The zoom link is https://ethz.zoom.us/j/362994444.
Best,
-joe
Abstract:
The unification of quantum mechanics and general relativity, two of the
most successful
theories in physics, poses immense difficulties, such as the problem of
time. Recent works
have started to investigate low energy effects at this interface, …
[View More]probing
the quantum nature of
spacetime. This thesis starts with the assumption that a superposition of
masses leads to a
superposition of spacetimes. We formalize this notion under the additional
assumption of low
velocities. To illustrate these ideas, we simulate the gravitational
quantum switch. We then
present a scheme to map out spacetime using signals, as an operational way
to distinguish
spacetimes. The second part brings clocks into the picture. We derive a
decoherence effect
of a large mass near a clock and a minimal uncertainty for a clock in a
gravitational field.
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Hi all,
Tomorrow Paula Belzig will present her master's thesis on de Finetti
theorems, which is joint between Uni Köln and ETH. See below for title and
abstract.
Best,
-joe
Title: Studying Stabilizer de Finetti Theorems - Applications in Quantum
Information Processing
Abstract: If a quantum state is invariant under permutations of its
subsystems, it is a well-known and widely used result in quantum theory
that its marginal can be approximated by a mixture of tensor powers of a
state on a …
[View More]single subsystem. Recently, it has been discovered by Gross,
Nezami and Walter that a similar observation can be made for a larger
symmetry group than permutations: states that are invariant under
stochastic orthogonal symmetry are approximated by tensor powers of
stabilizer states, with an exponentially smaller approximation error than
previously possible.
Quantum de Finetti theorems find application in various contexts, in
particular in QKD and in numerical separability tests, which we explore
here using the stabilizer de Finetti theorem instead of the
permutation-based version. On the one hand, when analyzing a QKD protocol
with stochastic orthogonal invariance, we find that its security against
general, most powerful attacks can be inferred from its security against
collective attacks with a smaller change in the security parameter compared
to permutation-based considerations. On the other hand, we show that the
stabilizer de Finetti theorem can lead to a semi-definite programming
hierarchy approximating separable and partly stabilizer states, which
facilitates studying the optimal Clifford encoder or decoder for a given
quantum error correction procedure.
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Hi all,
Tomorrow Yuxiang will tell us about his latest preprint (see below).
The zoom link is https://ethz.zoom.us/j/362994444.
Best,
-joe
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Ultimate limit on time signal generation
The generation of time signals is a fundamental task in science. Here I
will talk about the relation between the quality of a time signal and the
physics of the system that generates it. According to quantum theory, any
time signal can be decomposed into individual quanta that lead to single
detection …
[View More]events. Our main result is a bound on how sharply peaked in time
these events can be, which depends on the dimension of the signal
generator. I will also discuss how the result may lead to a more accurate
clock in the future.
The talk will be based on https://arxiv.org/abs/2004.07857.
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