We propose a two-qubit gate based on dipolar exchange interactions between individually addressable ultracold polar molecules in an array of optical dipole traps. Our proposal treats the full ...Hamiltonian of the
1
Σ
+
molecule NaCs, utilizing a pair of nuclear spin states as storage qubits. A third rotationally excited state with rotation-hyperfine coupling enables switchable electric dipolar exchange interactions between two molecules to generate an iSWAP gate. All three states are insensitive to external magnetic and electric fields. Impacts on gate fidelity due to coupling to other molecular states, imperfect ground-state cooling, blackbody radiation and vacuum spontaneous emission are small, leading to potential fidelity above 99.99% in a coherent quantum system that can be scaled by purely optical means.
Proposed molecular quantum gate takes advantage of internal coherence and resonant electric dipolar interaction with high fidelity and optical scalability.
In many chemical reactions, the transformation from reactants to products is mediated by transient intermediate complexes. For gas-phase reactions involving molecules with a few atoms, these ...complexes typically live on the order of 10 ps or less before dissociating, and are therefore rarely influenced by external processes. Here, we demonstrate that the transient intermediate complex K2Rb2*, formed from collisions between ultracold KRb molecules, undergoes rapid photo-excitation in the presence of a continuous-wave laser source at 1,064 nm, a wavelength commonly used to confine ultracold molecules. These excitations are facilitated by the exceptionally long lifetime of the complex under ultracold conditions. Indeed, by monitoring the change in the complex population after the sudden removal of the excitation light, we directly measure the lifetime of the complex to be 360 ± 30 ns, in agreement with our calculations based on the Rice–Ramsperger–Kassel–Marcus (RRKM) statistical theory. Our results shed light on the origin of the two-body loss widely observed in ultracold molecule experiments. Additionally, the long complex lifetime, coupled with the observed photo-excitation pathway, opens up the possibility to spectroscopically probe the structure of the complex with high resolution, thus elucidating the reaction dynamics.A transient intermediate complex in a chemical reaction—formed from collisions between molecules with a few atoms—is observed under ultracold conditions. Its lifetime can be directly measured after suppression of the photo-excitation process.
Roadmap on STIRAP applications Bergmann, Klaas; Nägerl, Hanns-Christoph; Panda, Cristian ...
Journal of physics. B, Atomic, molecular, and optical physics,
09/2019, Letnik:
52, Številka:
20
Journal Article
Recenzirano
Odprti dostop
STIRAP (stimulated Raman adiabatic passage) is a powerful laser-based method, usually involving two photons, for efficient and selective transfer of populations between quantum states. A particularly ...interesting feature is the fact that the coupling between the initial and the final quantum states is via an intermediate state, even though the lifetime of the latter can be much shorter than the interaction time with the laser radiation. Nevertheless, spontaneous emission from the intermediate state is prevented by quantum interference. Maintaining the coherence between the initial and final state throughout the transfer process is crucial. STIRAP was initially developed with applications in chemical dynamics in mind. That is why the original paper of 1990 was published in The Journal of Chemical Physics. However, from about the year 2000, the unique capabilities of STIRAP and its robustness with respect to small variations in some experimental parameters stimulated many researchers to apply the scheme to a variety of other fields of physics. The successes of these efforts are documented in this collection of articles. In Part A the experimental success of STIRAP in manipulating or controlling molecules, photons, ions or even quantum systems in a solid-state environment is documented. After a brief introduction to the basic physics of STIRAP, the central role of the method in the formation of ultracold molecules is discussed, followed by a presentation of how precision experiments (measurement of the upper limit of the electric dipole moment of the electron or detecting the consequences of parity violation in chiral molecules) or chemical dynamics studies at ultralow temperatures benefit from STIRAP. Next comes the STIRAP-based control of photons in cavities followed by a group of three contributions which highlight the potential of the STIRAP concept in classical physics by presenting data on the transfer of waves (photonic, magnonic and phononic) between respective waveguides. The works on ions or ion strings discuss options for applications, e.g. in quantum information. Finally, the success of STIRAP in the controlled manipulation of quantum states in solid-state systems, which are usually hostile towards coherent processes, is presented, dealing with data storage in rare-earth ion doped crystals and in nitrogen vacancy (NV) centers or even in superconducting quantum circuits. The works on ions and those involving solid-state systems emphasize the relevance of the results for quantum information protocols. Part B deals with theoretical work, including further concepts relevant to quantum information or invoking STIRAP for the manipulation of matter waves. The subsequent articles discuss the experiments underway to demonstrate the potential of STIRAP for populating otherwise inaccessible high-lying Rydberg states of molecules, or controlling and cooling the translational motion of particles in a molecular beam or the polarization of angular-momentum states. The series of articles concludes with a more speculative application of STIRAP in nuclear physics, which, if suitable radiation fields become available, could lead to spectacular results.
We aimed to systematically review the literature on apical pelvic organ prolapse surgery with uterine preservation compared with prolapse surgeries including hysterectomy and provide evidence-based ...guidelines.
The sources for our data were MEDLINE, Cochrane, and clinicaltrials.gov databases from inception to January 2017.
We accepted randomized and nonrandomized studies of uterine-preserving prolapse surgeries compared with those involving hysterectomy.
Studies were extracted for participant information, intervention, comparator, efficacy outcomes, and adverse events, and they were individually and collectively assessed for methodological quality. If 3 or more studies compared the same surgeries and reported the same outcome, a meta-analysis was performed.
We screened 4467 abstracts and identified 94 eligible studies, 53 comparing uterine preservation to hysterectomy in prolapse surgery. Evidence was of moderate quality overall. Compared with hysterectomy plus mesh sacrocolpopexy, uterine preservation with sacrohysteropexy reduces mesh exposure, operative time, blood loss, and surgical cost without differences in prolapse recurrence. Compared with vaginal hysterectomy with uterosacral suspension, uterine preservation in the form of laparoscopic sacrohysteropexy improves the C point and vaginal length on the pelvic organ prolapse quantification exam, estimated blood loss, postoperative pain and functioning, and hospital stay, but open abdominal sacrohysteropexy worsens bothersome urinary symptoms, operative time, and quality of life. Transvaginal mesh hysteropexy (vs with hysterectomy) decreases mesh exposure, reoperation for mesh exposure, postoperative bleeding, and estimated blood loss and improves posterior pelvic organ prolapse quantification measurement. Transvaginal uterosacral or sacrospinous hysteropexy or the Manchester procedure compared with vaginal hysterectomy with native tissue suspension both showed improved operative time and estimated blood loss and no worsening of prolapse outcomes with uterine preservation. However, there is a significant lack of data on prolapse outcomes >3 years after surgery, the role of uterine preservation in obliterative procedures, and longer-term risk of uterine pathology after uterine preservation.
Uterine-preserving prolapse surgeries improve operating time, blood loss, and risk of mesh exposure compared with similar surgical routes with concomitant hysterectomy and do not significantly change short-term prolapse outcomes. Surgeons may offer uterine preservation as an option to appropriate women who desire this choice during apical prolapse repair.
In optical dipole traps, the excited rotational states of a molecule may experience a very different light shift than the ground state. For particles with two polarizability components (parallel and ...perpendicular), such as linear
Σ molecules, the differential shift can be nulled by choice of elliptical polarization. When one component of the polarization vector is ±i2 times the orthogonal component, the light shift for a sublevel of excited rotational states ±approaches that of the ground state at high optical intensity. In this case, fluctuating trap intensity need not limit coherence between ground and excited rotational states.
Rapid progress in atomic, molecular, and optical (AMO) physics techniques enabled the creation of ultracold samples of molecular species and opened opportunities to explore chemistry in the ultralow ...temperature regime. In particular, both the external and internal quantum degrees of freedom of the reactant atoms and molecules are controlled, allowing studies that explored the role of the long-range potential in ultracold reactions. The kinetics of these reactions have typically been determined using the loss of reactants as proxies. To extend such studies into the short-range, we developed an experimental apparatus that combines the production of quantum-state-selected ultracold KRb molecules with ion mass and kinetic energy spectrometry, and directly observed KRb + KRb reaction intermediates and products M.-G. Hu and Y. Liu, et al., Science, 2019, 366, 1111. Here, we present the apparatus in detail. For future studies that aim for detecting the quantum states of the reaction products, we demonstrate a photodissociation based scheme to calibrate the ion kinetic energy spectrometer at low energies.
Introduction and hypothesis
We aimed to systematically review the literature on pelvic organ prolapse (POP) surgery with uterine preservation (hysteropexy). We hypothesized that different hysteropexy ...surgeries would have similar POP outcomes but varying adverse event (AE) rates.
Methods
MEDLINE, Cochrane, and
clinicaltrials.gov
databases were reviewed from inception to January 2018 for comparative (any size) and single-arm studies (
n
≥ 50) involving hysteropexy. Studies were extracted for participant characteristics, interventions, comparators, outcomes, and AEs and assessed for methodological quality.
Results
We identified 99 eligible studies: 53 comparing hysteropexy to POP surgery with hysterectomy, 42 single-arm studies on hysteropexy, and four studies comparing stage ≥2 hysteropexy types. Data on POP outcomes were heterogeneous and usually from <3 years of follow-up. Repeat surgery prevalence for POP after hysteropexy varied widely (0–29%) but was similar among hysteropexy types. When comparing sacrohysteropexy routes, the laparoscopic approach had lower recurrent prolapse symptoms odds ratio (OR) 0.18, 95% confidence interval (CI) 0.07–0.46), urinary retention (OR 0.05, 95% CI 0.003–0.83), and blood loss (difference −104 ml, 95% CI −145 to −63 ml) than open sacrohysteropexy. Laparoscopic sacrohysteropexy had longer operative times than vaginal mesh hysteropexy (difference 119 min, 95% CI 102–136 min). Most commonly reported AEs included mesh exposure (0–39%), urinary retention (0–80%), and sexual dysfunction (0–48%).
Conclusions
Hysteropexies have a wide range of POP recurrence and AEs; little data exist directly comparing different hysteropexy types. Therefore, for women choosing uterine preservation, surgeons should counsel them on outcomes and risks particular to the specific hysteropexy type planned.
Introduction and hypothesis
Several posterior compartment surgical approaches are used to address posterior vaginal wall prolapse and obstructed defecation. We aimed to compare outcomes for both ...conditions among different surgical approaches.
Methods
A systematic review was performed comparing the impact of surgical interventions in the posterior compartment on prolapse and defecatory symptoms. MEDLINE, Embase, and
ClinicalTrials.gov
were searched from inception to 4 April 2018. Randomized controlled trials, prospective and retrospective comparative and single-group studies of women undergoing posterior vaginal compartment surgery for vaginal bulge or bowel symptoms were included. Studies had to include both anatomical and symptom outcomes both pre- and post-surgery.
Results
Forty-six eligible studies reported on six surgery types. Prolapse and defecatory symptoms improved with native-tissue transvaginal rectocele repair, transanal rectocele repair, and stapled transanal rectocele repair (STARR) surgeries. Although prolapse was improved with sacrocolpoperineopexy, defecatory symptoms worsened. STARR caused high rates of fecal urgency postoperatively, but this symptom typically resolved with time. Site-specific posterior repairs improved prolapse stage and symptoms of obstructed defecation. Compared with the transanal route, native-tissue transvaginal repair resulted in greater improvement in anatomical outcomes, improved obstructed defecation symptoms, and lower chances of rectal injury, but higher rates of dyspareunia.
Conclusions
Surgery in the posterior vaginal compartment typically has a high rate of success for anatomical outcomes, obstructed defecation, and bulge symptoms, although these may not persist over time. Based on this evidence, to improve anatomical and symptomatic outcomes, a native-tissue transvaginal rectocele repair should be preferentially performed.
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