Hybrid architectures for terahertz molecular polaritonics.

Atoms and their different arrangements into molecules are nature's building blocks. In a regime of strong coupling, matter hybridizes with light to modify physical and chemical properties, hence creating new building blocks that can be used for avant-garde technologies. However, this regime relies on the strong confinement of the optical field, which is technically challenging to achieve, especially at terahertz frequencies in the far-infrared region. Here we demonstrate several schemes of electromagnetic field confinement aimed at facilitating the collective coupling of a localized terahertz photonic mode to molecular vibrations. We observe an enhanced vacuum Rabi splitting of 200 GHz from a hybrid cavity architecture consisting of a plasmonic metasurface, coupled to glucose, and interfaced with a planar mirror. This enhanced light-matter interaction is found to emerge from the modified intracavity field of the cavity, leading to an enhanced zero-point electric field amplitude. Our study provides key insight into the design of polaritonic platforms with organic molecules to harvest the unique properties of hybrid light-matter states.

Metasurface-Based Hybrid Optical Cavities for Chiral Sensing.

Quantum metasurfaces, i.e., two-dimensional subwavelength arrays of quantum emitters, can be employed as mirrors towards the design of hybrid cavities, where the optical response is given by the interplay of a cavity-confined field and the surface modes supported by the arrays. We show that stacked layers of quantum metasurfaces with orthogonal dipole orientation can serve as helicity-preserving cavities. These structures exhibit ultranarrow resonances and can enhance the intensity of the incoming field by orders of magnitude, while simultaneously preserving the handedness of the field circulating inside the resonator, as opposed to conventional cavities. The rapid phase shift in the cavity transmission around the resonance can be exploited for the sensitive detection of chiral scatterers passing through the cavity. We discuss possible applications of these resonators as sensors for the discrimination of chiral molecules. Our approach describes a new way of chiral sensing via the measurement of particle-induced phase shifts.

Linear optical elements based on cooperative subwavelength emitter arrays.

We describe applications of two-dimensional subwavelength quantum emitter arrays as efficient optical elements in the linear regime. For normally incident light, the cooperative optical response, stemming from emitter-emitter dipole exchanges, allows the control of the array's transmission, its resonance frequency, and bandwidth. Operations on fully polarized incident light, such as generic linear and circular polarizers as well as phase retarders can be engineered and described in terms of Jones matrices. Our analytical approach and accompanying numerical simulations identify optimal regimes for such operations and reveal the importance of adjusting the array geometry and of the careful tuning of the external magnetic fields amplitude and direction.

Preparation of Dräger Atlan A350 and General Electric Healthcare Carestation 650 anesthesia workstations for malignant hyperthermia susceptible patients.

BACKGROUND: Patients at risk of malignant hyperthermia need trigger-free anesthesia. Therefore, anesthesia machines prepared for safe use in predisposed patients should be free of volatile anesthetics. The washout time depends on the composition of rubber and plastic in the anesthesia machine. Therefore, new anesthesia machines should be evaluated regarding the safe preparation for trigger-free anesthesia. This study investigates wash out procedures of volatile anesthetics for two new anesthetic workstations: Dräger Atlan A350 and General Electric Healthcare (GE) Carestation 650 and compare it with preparation using activated charcoal filters (ACF). METHODS: A Dräger Atlan and a Carestation 650 were contaminated with 4% sevoflurane for 90 min. The machines were decontaminated with method (M1): using ACF, method 2 (M2): a wash out method that included exchange of internal parts, breathing circuits and soda lime canister followed by ventilating a test lung using a preliminary protocol provided by Dräger or method 3 (M3): a universal wash out instruction of GE, method 4 (M4): M3 plus exchange of breathing system and bellows. Decontamination was followed by a simulated trigger-free ventilation. All experiments were repeated with 8% desflurane contaminated machines. Volatile anesthetics were detected with a closed gas loop high-resolution ion mobility spectrometer with gas chromatographic pre-separation attached to the bacterial filter of the breathing circuits. Primary outcome was time until < 5 ppm of volatile anesthetics and total preparation time. RESULTS: Time to < 5 ppm for the Atlan was 17 min (desflurane) and 50 min (sevoflurane), wash out continued for a total of 60 min according to protocol resulting in a total preparation time of 96-122 min. The Carestation needed 66 min (desflurane) and 24 min (sevoflurane) which could be abbreviated to 24 min (desflurane) if breathing system and bellows were changed. Total preparation time was 30-73 min. When using active charcoal filters time to < 5 ppm was 0 min for both machines, and total preparation time < 5 min. CONCLUSION: Both wash out protocols resulted in a significant reduction of trace gas concentrations. However, due to the complexity of the protocols and prolonged total preparation time, feasibility in clinical practice remains questionable. Especially when time is limited preparation of the anesthetic machines using ACF remain superior.

Floquet engineering of molecular dynamics via infrared coupling.

We discuss Floquet engineering of dissipative molecular systems through periodic driving of an infrared-active vibrational transition, either directly or via a cavity mode. Following a polaron quantum Langevin equation approach, we derive correlation functions and stationary quantities showing strongly modified optical response of the infrared-dressed molecule. The coherent excitation of molecular vibrational modes in combination with the modulation of electronic degrees of freedom due to vibronic coupling can lead to both enhanced vibronic coherence and control over vibrational sideband amplitudes. The additional coupling to an infrared cavity allows for the controlled suppression of undesired sidebands, an effect stemming from the Purcell enhancement of vibrational relaxation rates.

Langevin Approach to Quantum Optics with Molecules.

We investigate the interaction between light and molecular systems modeled as quantum emitters coupled to a multitude of vibrational modes via a Holstein-type interaction. We follow a quantum Langevin equations approach that allows for analytical derivations of absorption and fluorescence profiles of molecules driven by classical fields or coupled to quantized optical modes. We retrieve analytical expressions for the modification of the radiative emission branching ratio in the Purcell regime and for the asymmetric cavity transmission associated with dissipative cross talk between upper and lower polaritons in the strong coupling regime. We also characterize the Förster resonance energy transfer process between donor-acceptor molecules mediated by the vacuum or by a cavity mode.

Energy transfer and correlations in cavity-embedded donor-acceptor configurations.

The rate of energy transfer in donor-acceptor systems can be manipulated via the common interaction with the confined electromagnetic modes of a micro-cavity. We analyze the competition between the near-field short range dipole-dipole energy exchange processes and the cavity mediated long-range interactions in a simplified model consisting of effective two-level quantum emitters that could be relevant for molecules in experiments under cryogenic conditions. We find that free-space collective incoherent interactions, typically associated with sub- and superradiance, can modify the traditional resonant energy transfer scaling with distance. The same holds true for cavity-mediated collective incoherent interactions in a weak-coupling but strong-cooperativity regime. In the strong coupling regime, we elucidate the effect of pumping into cavity polaritons and analytically identify an optimal energy flow regime characterized by equal donor/acceptor Hopfield coefficients in the middle polariton. Finally we quantify the build-up of quantum correlations in the donor-acceptor system via the two-qubit concurrence as a measure of entanglement.

Does the surgeon's experience have an impact on outcome after total arterial revascularization with composite T-grafts? A risk factor analysis.

OBJECTIVES: When composite T-grafting is performed, total arterial revascularization (TAR) can be accomplished with only two grafts. There is the belief that composite grafting poses a risk of graft failure due to its single inflow via the left internal thoracic artery (LITA). High surgical quality is essential for left internal thoracic artery preparation, T-grafting and length estimation. We investigated whether the surgeon's experience influences postoperative outcome. METHODS: We analysed the data of 1080 consecutive patients (88% male, age: 62 ± 9 years) who underwent composite T-grafting between 1996 and 2011 in our institution. Patients were operated on either by experienced surgeons (Group A) or by surgeons early on in their career (Group B). Primary end-points were mortality, myocardial ischaemia, graft dysfunction and low cardiac output syndrome. Secondary end-points were persistent neurologic deficits (PNDs), blood transfusions and re-thoracotomy. Logistic regression analysis was performed to reveal independent risk factors for adverse outcome. RESULTS: Patients in Group B had a lower logistic EuroSCORE (2.8 vs 2.3%; P < 0.05), longer operative times (cross-clamp time: 41 ± 11 vs 47 ± 14 min; P < 0.001) and received less anastomoses (3.2 ± 0.7 vs 3.1 ± 0.7, P = 0.005). Mortality was low in both groups (Group A 0.6% vs Group B 0.4%; P = 1.0). Myocardial ischaemia occurred in 2.3% (Group A) and 2.5% (Group B; P = 0.82). Graft dysfunction was seen in 0.6% (Group A) and 1.4% (Group B; P = 0.25). Incidence of postoperative low cardiac output syndrome was comparable (Group A 1.4% vs Group B 0.7%; P = 0.53). Both groups showed similar incidence of secondary end-points (persistent neurologic deficit: Group A 2.9 vs 3.2% in Group B; P = 0.84; re-thoracotomy: 1.6% in Group A vs 1.8% in Group B, P = 1.0). Blood transfusions were more common in Group B (P = 0.005). Less surgical experience could only be identified as an independent risk factor for blood transfusion (P = 0.001). CONCLUSIONS: Total arterial revascularization with composite T-grafts can be performed safely by surgeons with different surgical experience. Despite differences in surgical performance parameters (e.g. operation times, blood transfusions), complication rates were extremely low, irrespective of the surgeon's operative experience. Surgeons can be introduced to these procedures in an early phase of training.

Total Arterial Revascularization with Radial Artery T-grafts in Patients with Significant Left Main Stem Stenosis Is Not Associated with Higher Perioperative Risk.

BACKGROUND: Total arterial revascularization (TAR) has become a standard procedure for the treatment of coronary multivessel disease, due to the superior long-term patency rates of arterial grafts as compared with saphenous vein graft material. Controversies about the use of TAR in patients with left main coronary artery disease exist. Hence, we ought to determine whether left main coronary artery disease is a risk factor for early postoperative mortality and morbidity after TAR using the in situ left internal thoracic artery (LITA) and radial artery as composite T-graft. METHODS: A total of 904 consecutive patients were included in this retrospective study. They underwent first-time coronary artery bypass grafting surgery in our institution, receiving TAR using the in situ LITA and RA T-graft. Of these patients, 247 (27%) had left main coronary artery disease (Group LMSS) and 657 (73%) had no significant left main coronary artery stenosis (Group nLMSS). RESULTS: Results were comparable. Mortality and perioperative myocardial infarction rates were 0.4% LMSS versus 0.3% nLMSS, p = 1, and 2% LMSS versus 2% nLMSS, p = 0.81, respectively. Stroke rate, acute renal failure rate, and reoperation rates were 2% LMSS versus 1% nLMSS, p = 0.36, 7% LMSS versus 8% nLMSS, p = 0.41, and 2% LMSS versus 3% nLMSS, p = 0.5, respectively. Postoperative stay was shorter in the LMSS group (8.1 ± 4.3 days vs. 8.9 ± 6.1 days nLMSS, p = 0.048). CONCLUSION: Our perioperative results indicate that TAR in patients with left main stenosis is safe and feasible. Long-term results will have to be awaited to further evaluate prognostic outcome.