Demonstration of quantum-enhanced rangefinding robust against classical jamming.

We demonstrate a quantum-enhanced lidar capable of performing confident target detection and rangefinding in the presence of strong, time-varying classical noise whilst operating with over five orders of magnitude separation between signal and background levels and target reflectivities down to -52 dB. We use a log-likelihood-based framework to introduce a new protocol for dynamic background tracking, verifying resilience of our system to both fast- and slow-modulation jamming in regimes where a classical illumination-based system fails to find a target. These results demonstrate the advantage of exploiting quantum correlations for lidar applications, providing a clear route to implementation in real-world scenarios.

Randomized Benchmarking Using Nondestructive Readout in a Two-Dimensional Atom Array.

Neutral atoms are a promising platform for scalable quantum computing, however, prior demonstration of high fidelity gates or low-loss readout methods have employed restricted numbers of qubits. Using randomized benchmarking of microwave-driven single-qubit gates, we demonstrate average gate errors of 7(2)×10^{-5} on a 225 site atom array using conventional, destructive readout. We further demonstrate a factor of 1.7 suppression of the primary measurement errors via low-loss, nondestructive, and state-selective readout on 49 sites while achieving gate errors of 2(9)×10^{-4}.

Demonstration of a Quantum Gate Using Electromagnetically Induced Transparency.

We demonstrate a native CNOT gate between two individually addressed neutral atoms based on electromagnetically induced transparency. This protocol utilizes the strong long-range interactions of Rydberg states to enable conditional state transfer on the target qubit when operated in the blockade regime. An advantage of this scheme is it enables implementation of multiqubit CNOT^{k} gates using a pulse sequence independent of qubit number, providing a simple gate for efficient implementation of digital quantum algorithms and stabilizer measurements for quantum error correction. We achieve a loss corrected gate fidelity of F_{CNOT}^{cor}=0.82(6), and prepare an entangled Bell state with F_{Bell}^{cor}=0.66(5), limited at present by laser power. We present a number of technical improvements to advance this to a level required for fault-tolerant scaling.

Long working distance objective lenses for single atom trapping and imaging.

We present a pair of optimized objective lenses with long working distances of 117 mm and 65 mm, respectively, that offer diffraction limited performance for both Cs and Rb wavelengths when imaging through standard vacuum windows. The designs utilise standard catalog lens elements to provide a simple and cost-effective solution. Objective 1 provides NA = 0.175 offering 3 µm resolution whilst objective 2 is optimized for high collection efficiency with NA = 0.29 and 1.8 µm resolution. This flexible design can be further extended for use at shorter wavelengths by simply re-optimising the lens separations.

Storage and control of optical photons using Rydberg polaritons.

We use a microwave field to control the quantum state of optical photons stored in a cold atomic cloud. The photons are stored in highly excited collective states (Rydberg polaritons) enabling both fast qubit rotations and control of photon-photon interactions. Through the collective read-out of these pseudospin rotations it is shown that the microwave field modifies the long-range interactions between polaritons. This technique provides a powerful interface between the microwave and optical domains, with applications in quantum simulations of spin liquids, quantum metrology and quantum networks.

Correlated photon emission from multiatom Rydberg dark States.

We consider three-level atoms driven by two resonant light fields in a ladder scheme where the upper level is a highly excited Rydberg state. We show that the dipole-dipole interactions between Rydberg excited atoms prevents the formation of single particle dark states and leads to strongly correlated photon pairs from atoms separated by distances large compared to the emission wavelength. For a pair of atoms, this enables realization of an efficient photon-pair source with on average one pair every 30 µs.

Cooperative atom-light interaction in a blockaded Rydberg ensemble.

By coupling a probe transition to a Rydberg state using electromagnetically induced transparency (EIT) we map the strong dipole-dipole interactions onto an optical field. We characterize the resulting cooperative optical nonlinearity as a function of probe strength and density. We demonstrate good quantitative agreement between the experiment and an N-atom cooperative model for N=3 atoms per blockade sphere and the n=60 Rydberg state. The measured linewidth of the EIT resonance places an upper limit on the dephasing rate of the blockade spheres of <110 kHz.

A versatile and reliably reusable ultrahigh vacuum viewport.

We present a viewport for use in ultrahigh vacuum (UHV) based upon the preflattened solder seal design presented in earlier work [Cox et al., Rev. Sci. Instrum. 74, 3185 (2003)]. The design features significant modifications to improve long term performance. The windows have been leak tested to less than 10(-10) atm cm(3)/s. From atom number measurements in an optical dipole trap loaded from a vapor cell magneto-optical trap inside a vacuum chamber accommodating these viewports, we measure a trap lifetime of 9.5 s suggesting a pressure of around 10(-10) Torr limited by background rubidium vapor pressure. We also present a simplified design where the UHV seal is made directly to a vacuum pipe.

Evaluation of a 24-hour infusion of etidronate disodium for the treatment of hypercalcemia of malignancy.

BACKGROUND: Hypercalcemia is a serious and common complication of malignancy. Etidronate, a known inhibitor of osteoclastic bone resorption, is approved in the therapy of hypercalcemia of malignancy (HCM) at a dose of 7.5 mg/kg/day infused during a period of 2-4 hours on 3 consecutive days. A multicenter study was conducted to evaluate the safety and efficacy of a single 24-hour infusion of etidronate disodium in patients with HCM. METHODS: Selected patients with HCM had disease refractory to at least 24-hours of intravenous fluid (more than 3 l/day) with two albumin-adjusted serum calcium concentrations greater than 11.5 mg/dl drawn 24 hours apart before etidronate treatment. Thirty patients were enrolled; 13 received 25 mg/kg for 24 hours, 12 received 30 mg/kg for 24-hours, 3 received incorrect doses (2 overdoses, and 1 underdose) and 2 died of disease-related complications before day 7. Of the 25 evaluable patients, 15 were men and 10 were women. Median age was 53 years (range, 20-75 years). Twelve patients (6 in each treatment group) had confirmed skeletal metastases. RESULTS: During the week after treatment, the 25 mg/kg group had adjusted serum calcium levels fall from a mean preinfusion baseline of 13.3 +/- 0.3 mg/dl (plus or minus the standard error of the mean) to a mean nadir of 10.9 +/- 0.4 mg/dl (the average of each patient's lowest calcium values). The 30 mg/kg group had adjusted serum calcium levels fall from a mean preinfusion baseline of 13.8 +/- 0.4 mg/dl to a mean nadir of 10.5 +/- 0.3 mg/dl. The average day that nadir occurred was day 5.7 for the 25 mg/kg group and day 5.6 for the 30 mg/kg group. The mean maximum reduction (delta) derived from the patients' nadirs in the 25 mg/kg dose group was 2.5 +/- 0.4 mg/dl and 3.3 +/- 0.3 mg/dl for the 30 mg/kg dose. Time to effect (either a partial response defined as a 15% or greater decrease in the adjusted serum calcium from the preinfusion value or a complete eucalcemic response defined as a reduction to the laboratory's eucalcemic range) occurred on average on day 4.6 in the 25 mg/kg group and day 3.7 in the 30 mg/kg group. Nine of the 13 (69%) patients in the 25 mg/kg treatment group had either partial or complete response to the 24-hour infusion. Five of these patients (38% of the 13 patients) of the 25 mg/kg group had serum calcium levels fall to their laboratory's eucalcemic range before day 7 (a complete response), 4 (31%) had partial response only, and 4 had no response. In the 30 mg/kg group, 11 of 12 (92%) patients had at least partial responses. Eight of the 12 (67%) patients had adjusted serum calcium concentrations fall to the eucalcemic range by day 7, 3 (25%) had a partial response, and 1 had no response. Reported adverse experiences generally were attributable to the underlying disease. The reduction in the serum calcium throughout the week for the 30 mg/kg dose group was significantly greater than that for the 25 mg/kg group (analysis of variance, P < 0.0001). CONCLUSIONS: Etidronate, when administered intravenously at 30 mg/kg during a period of 24 hours, apparently was safe and effective in this study for treatment of hypercalcemia in patients with a wide variety of tumor types. This regimen may offer a more convenient method of administration than does standard etidronate therapy for the treatment of HCM.

Phase I-II trial of percutaneous intra-arterial cis-diamminedichloro platinum (II) for regionally confined malignancy.

Forty-nine patients with regionally confined recurrent malignancy were treated with intra-arterial cis-diamminedichloro platinum II in a Phase I-II trial. A safe starting dose of 120 mg/m2 was established. An overall response rate of 45% was noted with significant responses observed among patients with melanoma, sarcoma, breast carcinoma, and neuroblastoma. Side effects included transient renal and bone marrow toxicity as well as neurotoxicity and ototoxicity (6%), the latter usually with residual damage. The rational basis and advantages of treatment with intra-arterial cis-platinum are discussed.