# All

The real stabilizer fragment of quantum mechanics was shown to have a

complete axiomatization in terms of the angle-free fragment of the ZX-calculus.

This fragment of the ZXcalculus--although abstractly elegant--is stated in

terms of identities, such as spider fusion which generally do not have

interpretations as circuit transformations. We complete the category CNOT

generated by the controlled not gate and the computational ancillary bits,

presented by circuit relations, to the real stabilizer fragment of quantum

The variational quantum eigensolver is one of the most promising approaches

for performing chemistry simulations using noisy intermediate-scale quantum

(NISQ) processors. The efficiency of this algorithm depends crucially on the

ability to prepare multi-qubit trial states on the quantum processor that

either include, or at least closely approximate, the actual energy eigenstates

of the problem being simulated while avoiding states that have little overlap

This paper presents the thermal interpretation of quantum physics. The

insight from Part I of this series that Born's rule has its limitations --

hence cannot be the foundation of quantum physics -- opens the way for an

alternative interpretation -- the thermal interpretation of quantum physics. It

gives new foundations that connect quantum physics (including quantum

mechanics, statistical mechanics, quantum field theory and their applications)

to experiment. The thermal interpretation resolves the problems of the

Monte Carlo simulations are performed in classical phase space for a

one-dimensional quantum harmonic crystal. Symmetrization effects for spinless

bosons and fermions are quantified. The algorithm is tested for a range of

parameters against exact results that use 20,000 energy levels. It is shown

that the singlet mean field approximation is very accurate at high

temperatures, and that the pair mean field approximation gives a systematic

improvement in the intermediate and low temperature regime. The latter is

Optical clocks based on atoms and ions achieve exceptional precision and

accuracy, with applications to relativistic geodesy, tests of relativity, and

searches for dark matter. Achieving such performance requires balancing

competing desirable features, including a high particle number, isolation of

atoms from collisions, insensitivity to motional effects, and high duty-cycle

operation. Here we demonstrate a new platform based on arrays of ultracold

strontium atoms confined within optical tweezers that realizes a novel

This paper presents the measurement problem from the point of view of the

thermal interpretation of quantum physics introduced in Part II. The

measurement of a Hermitian quantity $A$ is regarded as giving an uncertain

value approximating the q-expectation $\langle A\rangle$ rather than (as

tradition wanted to have it) as an exact revelation of an eigenvalue of $A$.

Single observations of microscopic systems are (except under special

circumstances) very uncertain measurements only. The thermal interpretation

In the past decades, quantum plasmonics has become an active area due to its

potential applications in on-chip plasmonic devices for quantum information

processing. However, the fundamental physical process, i.e., how a quantum

state of light evolves in the photon-plasmon conversion process, has not been

clearly understood. Here, we report a complete characterization of the

plasmon-assisted extraordinary optical transmission process through quantum

process tomography. By inputting various coherent states to interact with the

We describe how an ensemble of four-level atoms in the diamond-type

configuration can be applied to create a fully controllable effective coupling

between two cavity modes. The diamond-type configuration allows one to use a

bimodal cavity that supports modes of different frequencies or different

circular polarisations, because each mode is coupled only to its own

transition. This system can be used for mapping a quantum state of one cavity

mode onto the other mode on demand. Additionally, it can serve as a fast

We investigate the Joule expansion of nonintegrable quantum systems that

contain bosons or spinless fermions in one-dimensional lattices. A barrier

initially confines the particles to be in half of the system in a thermal state

described by the canonical ensemble and is removed at time $t = 0$. We

investigate the properties of the time-evolved density matrix, the diagonal

ensemble density matrix and the corresponding canonical ensemble density matrix

with an effective temperature determined by the total energy conservation using

We aim to devise feasible, efficient verification schemes for bosonic

channels. To this end, we construct an average-fidelity witness that yields a

tight lower bound for average fidelity plus a general framework for verifying

optimal quantum channels. For both multi-mode unitary Gaussian channels and

single-mode amplification channels, we present experimentally feasible

average-fidelity witnesses and reliable verification schemes, for which sample

complexity scales polynomially with respect to all channel specification