Quasiparticle Poisoning of Superconducting Qubits from Resonant Absorption of Pair-Breaking Photons.

The ideal superconductor provides a pristine environment for the delicate states of a quantum computer: because there is an energy gap to excitations, there are no spurious modes with which the qubits can interact, causing irreversible decay of the quantum state. As a practical matter, however, there exists a high density of excitations out of the superconducting ground state even at ultralow temperature; these are known as quasiparticles. Observed quasiparticle densities are of order 1  μm^{-3}, tens of orders of magnitude greater than the equilibrium density expected from theory.

Hardware Implementation of Quantum Stabilizers in Superconducting Circuits.

Stabilizer operations are at the heart of quantum error correction and are typically implemented in software-controlled entangling gates and measurements of groups of qubits. Alternatively, qubits can be designed so that the Hamiltonian corresponds directly to a stabilizer for protecting quantum information. We demonstrate such a hardware implementation of stabilizers in a superconducting circuit composed of chains of π-periodic Josephson elements.

Acute pacing threshold elevation during simultaneous Micra leadless pacemaker implantation and AV node ablation: Clinical cases, computer model and practical recommendations.

Background: In patients with refractory atrial fibrillation (AF), atrioventricular nodal (AVN) ablation and permanent pacemaker implantation is recommended. The Micra Transcatheter Pacing System (Micra) is a single chamber leadless pacemaker (LPM) and thus offers the possibility of AV node (AVN) ablation in the same procedure. Pacing threshold (PT) elevation after radiofrequency (RF) ablation is a potential complication.

Leucocyte-derived micro-RNAs as candidate biomarkers in Brugada syndrome.

Aims: Risk stratification for sudden cardiac death in patients with Brugada syndrome remains a major challenge. Contemporary risk prediction models have only modest predictive value. The aim of this study was to assess the role of micro-RNAs from peripheral blood as candidate biomarkers in Brugada syndrome.

Superior vena cava tear during transvenous lead extraction: Medical management in hemodynamically stable patients.

Introduction: Superior vena cava (SVC) tear is the most lethal complication during transvenous lead extraction (TLE) with a mortality rate as high as 50%. Treatment involves aggressive attempts to maintain cardiac output and immediate sternotomy to localize and repair the vascular tear. Occlusion balloons have been developed to provisionally occlude the lacerated SVC and to provide hemodynamic stability allowing time for surgery.