Entanglement Assisted Probe of the Non-Markovian to Markovian Transition in Open Quantum System Dynamics.

We utilize a superconducting qubit processor to experimentally probe non-Markovian dynamics of an entangled qubit pair. We prepare an entangled state between two qubits and monitor the evolution of entanglement over time as one of the qubits interacts with a small quantum environment consisting of an auxiliary transmon qubit coupled to its readout cavity. We observe the collapse and revival of the entanglement as a signature of quantum memory effects in the environment. We then engineer the non-Markovianity of the environment by populating its readout cavity with thermal photons to show a transition from non-Markovian to Markovian dynamics, ultimately reaching a regime where the quantum Zeno effect creates a decoherence-free subspace that effectively stabilizes the entanglement between the qubits.

Quasi-Floquet Prethermalization in a Disordered Dipolar Spin Ensemble in Diamond.

Floquet (periodic) driving has recently emerged as a powerful technique for engineering quantum systems and realizing nonequilibrium phases of matter. A central challenge to stabilizing quantum phenomena in such systems is the need to prevent energy absorption from the driving field. Fortunately, when the frequency of the drive is significantly larger than the local energy scales of the many-body system, energy absorption is suppressed. The existence of this so-called prethermal regime depends sensitively on the range of interactions and the presence of multiple driving frequencies. Here, we report the observation of Floquet prethermalization in a strongly interacting dipolar spin ensemble in diamond, where the angular dependence of the dipolar coupling helps to mitigate the long-ranged nature of the interaction. Moreover, we extend our experimental observation to quasi-Floquet drives with multiple incommensurate frequencies. In contrast to a single-frequency drive, we find that the existence of prethermalization is extremely sensitive to the smoothness of the applied field. Our results open the door to stabilizing and characterizing nonequilibrium phenomena in quasiperiodically driven systems.

Speeding Up Entanglement Generation by Proximity to Higher-Order Exceptional Points.

Entanglement is a key resource for quantum information technologies ranging from quantum sensing to quantum computing. Conventionally, the entanglement between two coupled qubits is established at the timescale of the inverse of the coupling strength. In this Letter, we study two weakly coupled non-Hermitian qubits and observe entanglement generation at a significantly shorter timescale by proximity to a higher-order exceptional point. We establish a non-Hermitian perturbation theory based on constructing a biorthogonal complete basis and further identify the optimal condition to obtain the maximally entangled state. Our study of speeding up entanglement generation in non-Hermitian quantum systems opens new avenues for harnessing coherent nonunitary dissipation for quantum technologies.

Energetic Cost of Measurements Using Quantum, Coherent, and Thermal Light.

Quantum measurements are basic operations that play a critical role in the study and application of quantum information. We study how the use of quantum, coherent, and classical thermal states of light in a circuit quantum electrodynamics setup impacts the performance of quantum measurements, by comparing their respective measurement backaction and measurement signal to noise ratio per photon. In the strong dispersive limit, we find that thermal light is capable of performing quantum measurements with comparable efficiency to coherent light, both being outperformed by single-photon light. We then analyze the thermodynamic cost of each measurement scheme. We show that single-photon light shows an advantage in terms of energy cost per information gain, reaching the fundamental thermodynamic cost.

Single electrons on solid neon as a solid-state qubit platform.

Progress towards the realization of quantum computers requires persistent advances in their constituent building blocks-qubits. Novel qubit platforms that simultaneously embody long coherence, fast operation and large scalability offer compelling advantages in the construction of quantum computers and many other quantum information systems1-3. Electrons, ubiquitous elementary particles of non-zero charge, spin and mass, have commonly been perceived as paradigmatic local quantum information carriers. Despite superior controllability and configurability, their practical performance as qubits through either motional or spin states depends critically on their material environment3-5. Here we report our experimental realization of a qubit platform based on isolated single electrons trapped on an ultraclean solid neon surface in vacuum6-13. By integrating an electron trap in a circuit quantum electrodynamics architecture14-20, we achieve strong coupling between the motional states of a single electron and a single microwave photon in an on-chip superconducting resonator. Qubit gate operations and dispersive readout are implemented to measure the energy relaxation time T1 of 15 µs and phase coherence time T2 over 200 ns. These results indicate that the electron-on-solid-neon qubit already performs near the state of the art for a charge qubit21.

Efficiently fueling a quantum engine with incompatible measurements.

We propose a quantum harmonic oscillator measurement engine fueled by simultaneous quantum measurements of the noncommuting position and momentum quadratures of the quantum oscillator. The engine extracts work by moving the harmonic trap suddenly, conditioned on the measurement outcomes. We present two protocols for work extraction, respectively based on single-shot and time-continuous quantum measurements. In the single-shot limit, the oscillator is measured in a coherent state basis; the measurement adds an average of one quantum of energy to the oscillator, which is then extracted in the feedback step. In the time-continuous limit, continuous weak quantum measurements of both position and momentum of the quantum oscillator result in a coherent state, whose coordinates diffuse in time. We relate the extractable work to the noise added by quadrature measurements, and present exact results for the work distribution at arbitrary finite time. Both protocols can achieve unit work conversion efficiency in principle.

Topological Quantum State Control through Exceptional-Point Proximity.

We study the quantum evolution of a non-Hermitian qubit realized as a submanifold of a dissipative superconducting transmon circuit. Real-time tuning of the system parameters to encircle an exceptional point results in nonreciprocal quantum state transfer. We further observe chiral geometric phases accumulated under state transport, verifying the quantum coherent nature of the evolution in the complex energy landscape and distinguishing between coherent and incoherent effects associated with exceptional point encircling. Our work demonstrates an entirely new method for control over quantum state vectors, highlighting new facets of quantum bath engineering enabled through dynamical non-Hermitian control.

Decoherence-Induced Exceptional Points in a Dissipative Superconducting Qubit.

Open quantum systems interacting with an environment exhibit dynamics described by the combination of dissipation and coherent Hamiltonian evolution. Taken together, these effects are captured by a Liouvillian superoperator. The degeneracies of the (generically non-Hermitian) Liouvillian are exceptional points, which are associated with critical dynamics as the system approaches steady state. We use a superconducting transmon circuit coupled to an engineered environment to observe two different types of Liouvillian exceptional points that arise either from the interplay of energy loss and decoherence or purely due to decoherence. By dynamically tuning the Liouvillian superoperators in real time we observe a non-Hermiticity-induced chiral state transfer. Our study motivates a new look at open quantum system dynamics from the vantage of Liouvillian exceptional points, enabling applications of non-Hermitian dynamics in the understanding and control of open quantum systems.

Quantum Jumps in the Non-Hermitian Dynamics of a Superconducting Qubit.

We study the dynamics of a driven non-Hermitian superconducting qubit which is perturbed by quantum jumps between energy levels, a purely quantum effect with no classical correspondence. The quantum jumps mix the qubit states leading to decoherence. We observe that this decoherence rate is enhanced near the exceptional point, owing to the cube-root topology of the non-Hermitian eigenenergies. Together with the effect of non-Hermitian gain or loss, quantum jumps can also lead to a breakdown of adiabatic evolution under the slow-driving limit. Our study shows the critical role of quantum jumps in generalizing the applications of classical non-Hermitian systems to open quantum systems for sensing and control.

Weak Measurement of a Superconducting Qubit Reconciles Incompatible Operators.

Traditional uncertainty relations dictate a minimal amount of noise in incompatible projective quantum measurements. However, not all measurements are projective. Weak measurements are minimally invasive methods for obtaining partial state information without projection. Recently, weak measurements were shown to obey an uncertainty relation cast in terms of entropies. We experimentally test this entropic uncertainty relation with strong and weak measurements of a superconducting transmon qubit. A weak measurement, we find, can reconcile two strong measurements' incompatibility, via backaction on the state. Mathematically, a weak value-a preselected and postselected expectation value-lowers the uncertainty bound. Hence we provide experimental support for the physical interpretation of the weak value as a determinant of a weak measurement's ability to reconcile incompatible operations.

[High oblique sagittal split osteotomy]. / Clivage sagittal oblique court.

INTRODUCTION: Bilateral sagittal split osteotomy has become the standard mandibular surgery for the treatment of dental and facial deformities, even for small ones. The morbidity must be as low as possible. TECHNICAL NOTE: We describe a technique with reduced split surfaces, with an oblique bone section rather than a split. The bone is cut complete, on the posterior edge of the ramus, following an oblique line from above the lingula downward and laterally towards the supra-angular region. DISCUSSION: This section preserves the inferior alveolar nerve. It greatly decreases the risk of neurological sequels. Most mandibular movements are possible except for important advancement and elongation of the ramus.

3D evaluation of postoperative swelling using two different cooling methods following orthognathic surgery: a randomised observer blind prospective pilot study.

Orthognathic surgery is associated with side effects including severe postoperative swelling, pain, neurological dysfunction and trismus. The beneficial effects of localised cold treatment on postoperative swelling have been described. Topographical considerations make it difficult to quantify facial swelling. A new and promising method to measure facial swelling seems to be optical face scanning. This study aimed to evaluate the 3D optical scanner to measure soft tissue swelling following orthognathic surgery. Postoperative swelling was treated either with conventional cooling by cold packs or with the water-circulating cooling device Hilotherm Clinic. Secondary endpoints in each group included postoperative pain, neurological complaints, duration of hospital stay, trismus and patient satisfaction. The use of the cooling device by Hilotherm significantly reduced postoperative swelling, pain and hospital duration compared with conventional cooling. Postoperative trismus and satisfaction with the cooling method was significantly higher in the Hilotherm group compared with conventional cooling. No differences were observed concerning neurological score and outcome. In conclusion, 3D optical scanning is a simple and precise method of quantifying face swelling after orthognathic surgery. Hilotherm significantly reduces swelling and duration of hospital stay compared with conventional cooling.

[Surgically assisted rapid maxillary expansion. Effects on the nasal airways and nasal septum]. / Chirurgisch unterstützte transversale Oberkieferdistraktion. Auswirkungen auf Nasenwege und Nasenseptum.

BACKGROUND: Surgically assisted rapid maxillary expansion (SARME) is a standardized method to treat cross bites in maxillofacial surgery. Changes to the nasal airways are assumed due to the anatomic dependence between the palate and the nasal floor. PATIENTS AND METHODS: In this study 19 patients with a transverse deficit of the upper jaw underwent SARME. CT scans were performed 1 month pre- and 6 months postoperatively. Effects to the lower nasal airways, the nasal septum and the hard palate were subsequently evaluated. RESULTS: The mean distraction width of the upper jaws was 5.84 mm (SD 2.19) postoperatively. In addition to the dentoalveolar gain in width, a significant increase in the nasal floor was observed (p<0.001). The anterior part of the nasal floor was increased by 14.11%. An anterior-caudal tilt of the upper jaw was observed in the anterior part measuring 1.5 mm (SD 1.05). No significant deviation of the nasal septum occurred. CONCLUSION: SARME has a significant effect on ear, nose and throat medicine. Nasal airways enlarge significantly, while no significant deviation of the nasal septum is observed.

Cavity nonlinear optics at low photon numbers from collective atomic motion.

We report on Kerr nonlinearity and dispersive optical bistability of a Fabry-Perot optical resonator due to the displacement of ultracold atoms trapped within. In the driven resonator, such collective motion is induced by optical forces acting upon up to 10(5) 87Rb atoms prepared in the lowest band of a one-dimensional intracavity optical lattice. The longevity of atomic motional coherence allows for strongly nonlinear optics at extremely low cavity photon numbers, as demonstrated by the observation of both branches of optical bistability at photon numbers below unity.

Probing the quantum state of a guided atom laser pulse.

We describe bichromatic superradiant pump-probe spectroscopy as a tomographic probe of the Wigner function of a dispersing particle beam. We employed this technique to characterize the quantum state of an ultracold atomic beam, derived from a 87Rb Bose-Einstein condensate, as it propagated in a 2.5 mm diameter circular waveguide. Our measurements place an upper bound on the longitudinal phase space area occupied by the 3 x 10(5) atom beam of 9(1)Planck's constant and a lower bound on the coherence length of L>or=13(1) microm. These results are consistent with full quantum degeneracy after multiple orbits around the waveguide.

[CT assisted mandibular osteodistraction with reconstruction of the temporomandibular joint and two piece maxilla]. / CT-basierte Distraktion des Unterkiefers mit Gelenkrekonstruktion und Impaktation der Maxilla bei Kiefergelenkankylose.

BACKGROUND: The possibilities for computer assisted planning and its surgical conversion with stereolithographic templates are shown for complex maxillofacial surgical interventions. CASE REPORT: We describe the case of a patient with extreme micrognathia due to an ankylosis of the temporomandibular joint. In addition to the exact determination of the osteotomy lines on the mandibular angle and the segment osteotomy of the maxilla, vectors of the bidirectional osteodistraction were also predictable. CONCLUSION: In comparison with the conventional procedures, computer assisted planning achieved a much higher degree of precision and safety with reduced complication rates. The CMF module is a component of the SimPlant software which enables the precise planning of osteotomies and osteodistractions.

Shock wave treatment of salivary duct stones: substantial progress with a minilithotripter.

Extracorporeal shock wave lithotripsy has recently been introduced as the first non-operative treatment alternative for patients with sialolithiasis. Using conventional multipurpose lithotripters, however, successful treatment was achieved in only 36%-53% of patients. Therefore we developed an miniaturized lithotripter meeting the special requirements for extracorporeal shock wave treatment in the head and neck region. During a 1-year prospective trial clinical efficacy and safety were compared in 40 patients treated with a conventional electromagnetic lithotripter (group A) to 33 patients treated with the newly developed, miniaturized device (group B). The groups did not differ statistically regarding stone size or number or the proportion of stones located in the submandibular or parotid gland. Successful stone targeting, a prerequisite for shock wave treatment, was achieved by means of in-line ultrasonography in 30 of the 40 patients in group A and in 29 of 33 patients of group B. The number of shock wave impulses administered per session and the maximum shock wave intensities did not differ in the two groups. Significantly more frequent treatments with a longer mean duration of each session were required in group A (2.4 +/- 1.0 treatments, 47 +/- 11 min) than in group B (1.9 +/- 0.7 treatments, 28 +/- 9 min; P < 0.05). After a 3 month follow-up significantly more patients were free of stones in group B (22/33) than in group A (16/40; P < 0.05). Correspondingly, the number of patients free of complaints was significantly higher in group B (27/33) than in group A (22/40; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy, risks, and limits of extracorporeal shock wave lithotripsy for salivary gland stones.

Stones of the salivary glands may cause recurrent swelling, ascending inflammation, and colic-like pain. Previously, in order to get rid of these stones, the gland usually had to be removed surgically in spite of the associated risks to adjacent structures, especially the facial nerve. We treated 104 salivary gland stones in patients 14 to 78 years old using the Storz Modulith SL 10 lithotripter. Each session (average 3.6 per patient) consisted of 1000 impulses at 2 Hz and 16 to 18 kV. No anesthesia was required. Earplugs were applied to patients being treated for parotid gland stones. With the aid of SWL and drug-induced salivation, 17 (59%) of the patients with parotid gland stones and 42 (56%) of those with submandibular gland stones obtained either total stone clearance or sufficient fragmentation to permit spontaneous passage. Four patients required surgery. The remaining patients are still being treated. The noninvasive SWL for salivary gland stones is noninvasive and painless and has a considerable success rate. It can be performed on an outpatient basis.

[Angiolipoma of the maxillary sinus as a cause of recurring sinusitis-like symptoms]. / Angiolipom der Kieferhöhle als Ursache rezidivierender sinusitischer Beschwerden.

A review of the literature shows that intraoral lipomas are more common than they are generally believed to be. The clinical course of a case with unusual localization, size and clinical manifestation of an angiolipoma of the maxillary sinus is described. Differential diagnosis with other types of intraoral lipomas is made.