# All

Single shot error correction is a technique for correcting physical errors

using only a single round of noisy measurements, such that any residual noise

affects a small number of qubits. Not all error correcting codes support

single-shot error correction and until recently all known cases have been

topological codes in 3 or more dimensions. We establish a general theory of

single-shot error correction that is not limited to topological codes. A

crucial property is found to be code soundness from the literature on locally

We present a new scheme for teleporting a quantum state between two parties

whose local reference frames are misaligned by the action of a finite symmetry

group. Unlike other proposals, our scheme requires the same amount of classical

communication and entangled resources as conventional teleportation, does not

reveal any reference frame information, and is robust against changes in

reference frame alignment while the protocol is underway. The mathematical

Quantum microwave photonics aims at generating, routing, and manipulating

propagating quantum microwave fields in the spirit of optical photonics. To

this end, the strong nonlinearities of superconducting quantum circuits can be

used to either improve or move beyond the implementation of concepts from the

optical domain. In this context, the design of a well-controlled broadband

environment for the superconducting quantum circuits is a central task. In this

work, we place a superconducting transmon qubit in one arm of an on-chip

In this letter, we investigate the quantum optical properties of

driven-dissipative nonlinear systems in a cascade configuration. We show that

pumping a nonlinear system with a state having a noncoherent statistics, can

improve the antibunching of the output state and, consequently, the

nonclassicality of the whole system. Furthermore, we show that is possible to

generate entanglement through dissipative coupling. These results applies to a

broad category of physical systems with a Kerr-like non-linearity, from Rydberg

In this work we introduce the randomness which is truly quantum mechanical in

nature arising as an act of measurement. For a composite classical system we

have the joint entropy to quantify the randomness present in the total system

and that happens to be equal to the sum of the entropy of one subsystem and the

conditional entropy of the other subsystem given we know the first system. The

same analogy caries over to the quantum setting by replacing the Shannon

We argue that space and space-time emerge as a consequence of dynamical

collapse of the wave function of macroscopic objects. Locality and separability

are properties of our approximate, emergent universe. At the fundamental level,

space-time is non-commutative, and dynamics is non-local and non-separable.

We investigate the finite-size Dicke model with photon leakage. It is shown

that the symmetry breaking states, which are characterized by non-vanishing

$\langle \hat{a} \rangle \neq 0$ and correspond to the ground states in the

superradiant phase in the thermodynamic limit, are stable, while the

eigenstates of the isolated finite-size Dicke Hamiltonian conserve parity

symmetry. We introduce and analyze an effective master equation that describes

the dynamics of a pair of the symmetry breaking states that are the degenerate

We find a simple model of an insulating state of a quantum wire which has a

single isolated edge mode. We argue that, when brought to proximity, the edge

modes on independent wires naturally form Bell entangled states which could be

used for elementary quantum processes such as teleportation. We give an example

of an algorithm which teleports the spin state of an electron from one quantum

wire to another.

Recent computations involving quantum processing units (QPUs) have

demonstrated a series of challenges inherent to hybrid classical-quantum

programming, compilation, execution, and verification and validation. Despite

considerable progress, system-level noise, limited low-level instructions sets,

remote access models, and an overall lack of portability and classical

integration presents near-term programming challenges that must be overcome in

order to enable reliable scientific quantum computing and support robust

We experimentally demonstrate a real-time optical quantum random number

generator by measuring vacuum fluctuation. Analysis towards the impact of

practical system components is done to obtain higher min-entropy, in which

min-entropy represents extractable quantum randomness. The corresponding

min-entropy is calculated as 6.93 bits per sample in our experiment when system

components' parameters are suitably adjusted. To bridge the speed gap between

the fast randomness generation and the slow randomness extraction, we propose