# All

The equivalence principle in combination with the special relativistic

equivalence between mass and energy, $E=mc^2$, is one of the cornerstones of

general relativity. However, for composite systems a long-standing result in

general relativity asserts that the passive gravitational mass is not simply

equal to the total energy. This seeming anomaly is supported by all explicit

derivations of the dynamics of bound systems, and is only avoided after

time-averaging. Here we rectify this misconception and derive from first

Parity-Time (PT) symmetric quantum mechanics is a complex extension of

conventional Hermitian quantum mechanics in which physical observables possess

a real eigenvalue spectrum. However, an experimental demonstration of the true

quantum nature of PT symmetry has been elusive thus far, as only

single-particle physics has been exploited to date. In our work, we demonstrate

two-particle quantum interference in a PT-symmetric system. We employ

integrated photonic waveguides to reveal that PT-symmetric bunching of

Scrambling of quantum information is the process by which information

initially stored in the local degrees of freedom of a quantum many-body system

spreads over its many-body degrees of freedom, becoming inaccessible to local

probes and thus apparently lost. Scrambling and entanglement are key concepts

reconciling seemingly unrelated behaviors including thermalization of isolated

quantum systems and information loss in black holes, and have revolutionized

One of the most important tasks in modern quantum science is to coherently

control and entangle many-body systems, and to subsequently use these systems

to realize powerful quantum technologies such as quantum-enhanced sensors.

However, many-body entangled states are difficult to prepare and preserve since

internal dynamics and external noise rapidly degrade any useful entanglement.

Here, we introduce a protocol that counterintuitively exploits inhomogeneities,

We introduce a multi-step protocol for optical quantum state engineering that

performs as deterministic "bright quantum scissors" (BQS), namely truncates an

arbitrary input quantum state to have at least a certain number of photons. The

protocol exploits single-photon pulses and is based on the effect of

single-photon Raman interaction, which is implemented with a single three-level

$\Lambda$ system (e.g. a single atom) Purcell-enhanced by a single-sided

cavity. A single step of the protocol realises the inverse of the bosonic

We theoretically investigate the possibility of performing high precision

estimation of an externally imposed acceleration using scalar bosons in a

single-well trap. We work at the level of a two-mode truncation, valid for weak

to intermediate two-body interaction couplings.The splitting process into two

modes is in our model entirely caused by the interaction between the

constituent bosons and is hence neither due to an externally imposed

double-well potential nor due to populating a spinor degree of freedom. The

We may infer a transition $|n \rangle \to |m \rangle$ between energy

eigenstates of an open quantum system by observing the emission of a photon of

Bohr frequency $\omega_{mn} = (E_n-E_m) / \hbar$. In addition to the

"collapses" to the state $|m\rangle$, the measurement must also have brought

into existence the pre-measurement state $|n \rangle$. As quantum trajectories

are based on past observations, the condition state will jump to $| m \rangle$,

but the state $|n\rangle$ does not feature in any essential way. We resolve

We introduce an approach to find the Tomita-Takesaki modular flow for

multi-component regions in chiral conformal field theory. Our method is based

only locality (or braid-relations) of primary fields and the so-called

Kubo-Martin-Schwinger (KMS) condition. These methods can be used to transform

the problem to a Riemann-Hilbert problem on a covering of the complex plane cut

along the regions. The method for instance gives a formula for the modular flow

in the case of a thermal state for the free fermion net, but is in principle

We study the quasiparticle excitation and quench dynamics of the

one-dimensional transverse-field Ising model with power-law ($1/r^{\alpha}$)

interactions. We find that long-range interactions give rise to a confining

potential, which couples pairs of domain walls (kinks) into bound

quasiparticles, analogous to mesonic bound states in high-energy physics. We

show that these quasiparticles have signatures in the dynamics of order

parameters following a global quench and the Fourier spectrum of these order

In compressed sensing one uses known structures of otherwise unknown signals

to recover them from as few linear observations as possible. The structure

comes in form of some compressibility including different notions of sparsity

and low rankness. In many cases convex relaxations allow to efficiently solve

the inverse problems using standard convex solvers at almost-optimal sampling

rates. A standard practice to account for multiple simultaneous structures in