Stand-alone vacuum cell for compact ultracold quantum technologies

Ultracold atoms in optical lattices provide an extremely clean and controllable setting to explore quantum many-body phases of matter. Here we give a brief review of the strong-correlation physics that has been realized using such ultracold atoms in optical lattices ranging from the realization of Hubbard models to studies of quantum magnetism and the detection of single atoms with lattice site resolution. All this has opened up fundamentally new opportunities for the investigation of quantum many-body systems. Introduction Over the past years, ultracold atoms in optical lattices have emerged as versatile new systems to explore the physics of quantum many-body systems. On the one hand, they can be helpful in gaining a better understanding of known phases of matter and their dynamical behavior; on the other hand, they allow one to realize completely novel quantum systems that have not been studied before in nature [1, 2, 3]. Commonly, the approach of exploring quantum many-body systems in such a way is referred to as “quantum simulations.” Examples of some of the first strongly interacting many-body phases that have been realized both in lattices and in the continuum include the quantum phase transition from a superfluid to a Mott insulator [4, 5, 6], fermionic Mott insulators [7, 8], the achievement of a Tonks- Girardeau gas [9, 10], and the realization of the Bose-Einsten condensate (BEC)– Bardeen-Cooper-Schrieffer (BCS) crossover (see also Chapter 12) in Fermi gas mixture [11] using Feshbach resonances [12]. In almost all of these experiments, detection was limited to time-of-flight imaging or more refined derived techniques that mainly characterized the momentum distribution of the quantum gas [2]. For several years, researchers in the field have therefore aspired to employ in situ single-particle detection methods for the analysis of ultracold quantum gases. Only recently has it become possible to implement such imaging techniques, marking a milestone for the characterization and manipulation of ultracold quantum gases [13, 14, 15, 16, 17]. In our discussion, we will focus on one of the most successful of these techniques based on high-resolution fluorescence imaging. Despite being a rather new technique, such quantum gas microscopy has already proven to be an enabling technology for probing and manipulating quantum many-body systems. For the first time, controllable and strongly interacting many-body systems, as realized with ultracold atoms, could be observed on a local scale [17, 16].

An index of peripheral vascular resistance, derived from directly measured arterial pressure, has been developed and tested in an animal model. Assuming a mono-exponential character for diastole, the time constant for direct arterial pressure decay in the central aorta was obtained with high-fidelity recording techniques from six anaesthetized dogs. Changes in peripheral resistance were induced by infusion of phenylephrine or nitroprusside. The time constant correlated well with resistance determined from 1-min averages of pressure divided by integrated electromagnetic flow (r = 0.845). A portable system used for direct arterial pressure recording in ambulant outpatients yielded a mean correlation of 0.822 with resistance. In a study of patients undergoing cardiac catheterization, a time constant obtained from the brachial artery (the site of pressure recording in the ambulant subjects) correlated well with the aortic time constant (n = 6, r = 0.964). The results of the present work suggest that the time constant derived from direct arterial pressure waveform may be a useful index in the evaluation of the peripheral vascular resistance. Furthermore, with the help of the portable system it might be used for the continuous monitoring of resistance changes in ambulatory subjects.

The thesis studies Photon-Assisted Tunneling (PAT) in a system of ultracold atoms in a triple-well potential, utilizing Bose-Hubbard and Gross-Pitaevskii models. Simulations reveal that an ac-driving field influence tunneling dynamics, enabling quantum self-trapping and PAT. The study extends to open quantum systems, analyzing PT-symmetric setups with balanced gain and loss, showcasing PAT’s role in quantum control and potential applications in ultracold atom systems and quantum optics.

A ultralow noise magnetic field is essential for many branches of scientific research. Examples include experiments conducted on ultracold atoms, quantum simulations, and precision measurements. In ultracold atom experiments specifically, a bias magnetic field will often serve as a quantization axis and be applied for Zeeman splitting. As atomic states are usually sensitive to magnetic fields, a magnetic field characterized by ultralow noise as well as high stability is typically required for experimentation. For this study, a bias magnetic field is successfully stabilized at 14.5 G, with the root mean square value of the noise reduced to 18.5 μG (1.28 ppm) by placing μ-metal magnetic shields together with a dynamical feedback circuit. Long-time instability is also regulated consistently below 7 μG. The level of noise exhibited in the bias magnetic field is further confirmed by evaluating the coherence time of a Bose-Einstein condensate characterized by Rabi oscillation. It is concluded that this approach can be applied to other physical systems as well.

Ultracold Atoms and Quantum Measurement Processes

Non-Gaussian correlations in a pure state are inextricably linked with certain nonclassical features, such as a non-positive-definite Wigner function. In a commonly used simulation technique in ultracold atoms and quantum optics, known as the truncated Wigner method, the quantum dynamics is mapped to stochastic trajectories in phase space, governed by a positive approximation to the true Wigner distribution. The question thus arises: How accurate is this approach in predicting truly nonclassical behavior? In this article, we benchmark the ability of the truncated Wigner phase-space method to reproduce the non-Gaussian statistics of the single-mode anharmonic oscillator. We find that the this method can reliably predict departures from Gaussian statistics over a wide range of particle numbers, whereas the positive-$P$ representation, which involves no approximations, is limited by rapidly growing statistical uncertainty. The truncated Wigner function, furthermore, is able to reproduce the non-Gaussian correlations while satisfying the condition for purity.

The utilization of Ramsey interferometry via coherent population trapping (CPT), which enables the optical interrogation of microwave transitions without the reliance on microwave cavities, plays a crucial role in the advancement of compact and low-power quantum sensors. Particularly, high-resolution CPT-Ramsey spectroscopy of alkali-metal atoms has found extensive application in constructing miniaturized quantum sensors like atomic magnetometers and atomic clocks. Due to their well-defined environment and extended coherence time, cold atoms offer enhanced sensitivity and precision in CPT-Ramsey interferometry. This review comprehensively examines CPT-Ramsey interferometry with cold atoms, encompassing both conventional and multi-pulse techniques, and explores their potential applications in practical quantum sensors.

A portable, highly sensitive, and continuous ammonia gas monitoring system was developed with a microfluidic chip. The system consists of a main unit, a gas pumping unit, and a computer which serves as an operation console. The size of the system is 45 cm width × 30 cm depth × 30 cm height, and the portable system was realized. A highly efficient and stable extraction method was developed by utilizing an annular gas/liquid laminar flow. In addition, a stable gas/liquid separation method with a PTFE membrane was developed by arranging a fluidic network in three dimensions to achieve almost zero dead volume at the gas/liquid extraction part. The extraction rate was almost 100% with a liquid flow rate of 3.5 μL/min and a gas flow rate of 100 mL/min (contact time of ~15 ms), and the concentration factor was 200 times by calculating the NH(3) concentration (w/w unit) in the gas and liquid phases. Stable phase separation and detection was sustained for more than 3 weeks in an automated operation, which was sufficient for the monitoring application. The lower limit of detection calculated based on a signal-to-noise ratio of 3 was 84 ppt, which showed good detectability for NH(3) analysis. We believe that our system is a very powerful tool for gas analysis due to the advantages of portable size, high sensitivity, and continuous monitoring, and it is particularly useful in the semiconductor field.

A preliminary design for a broadband, multiple quantum well (MQW), distributed Bragg reflector (DBR), electronically tunable laser diode array has been developed for implementation into optical memory configurations. The proposed MQW DBR diode array and a waveguide hologram with a blazed grating and/or holographic diffraction grating will be integrated into a photonic random optical memory access (PROMAC) device. PROMAC is a low inertia, low power, sub-nanosecond, parallel (e.g. 64 bit wide), wavelength addressing device which exploits free space optical interconnects. The MQW DBR laser diode array will enhance the performance of PROMAC by offering advantages in speed, spectral resolution, holographic separation and scan efficiency. An increase in speed as well as a decrease in power consumption can also be realized. Thus, increased storage densities and faster access rates can be achieved.

PON versus AON: Which is the best solution to offload core network by peer-to-peer traffic localization

Due to an increase in home appliances (HAs) the overall power consumption in home tends to grow and leads an increasing risk of losing stability. In this paper, we propose a system model for smart homes to control maximum power consumption by HAs based on HA priority. The proposed system consists of smart electric sensors (SESs), power provisioning controller (PPC) and HAs. The role of PPC is to gather ON/OFF status from each HA and instantaneous consuming power level from SES, and to send control signal back to each HA. After gathering information, along with HA priority, computes a final target power level for each HA is not a hard task. However, when ON/OFF status of HAs change, we may need to reassign an amount of consuming power from one HA to another, and the transient behavior due to such reassignment of power is not simple. This paper proposes a system to control the maximum total power consumption in detailed transient behavior considering heterogeneous HAs with different time constants. In order to guarantee the maximum power limit, we will compute the remaining power, and reassign it to HAs as their temporal target power levels. Simulation results show the effectiveness of our system in managing maximum power consumption.

Magnetic trapping of laser-cooled neutral atoms has been demonstrated at NBS and is progressing in other laboratories. Confinement of any object requires exchanging kinetic for potential energy, and for neutral atoms, this necessarily derives from shifts of internal energy levels. This is implemented through the force experienced by the atomic magnetic moment in a carefully designed, highly inhomogeneous field. Since magnetic fields of convenient strength can shift atomic energy levels by only a few gigahertz (temperature ≌ 0.1 K), neutral atom traps are very shallow and must be loaded with very cold atoms. We present some motivations for using magnetic traps and then discuss the constraints and optimal configurations of various arrangements. For example, no trap can be isotropic. Next we discuss both the classical and quantum mechanical motions of trapped atoms. These motions are important for at least two reasons: First, several schemes under study for further cooling depend on knowing the position and velocity of the atoms, as well as the vector field at each point along the orbit. Second, magnetic traps depend on the atomic moment remaining aligned with the field as the atom orbits in the trap, and this precludes rapid motion through a low-field region.

Optical technologies represent the main bet for future communication systems. Among the others, digital subsystems for optical processing are of great interest thanks to their intrinsic properties in terms of bandwidth, transparency, immunity to the electromagnetic interference, cost, power consumption, as well as robustness in hostile environment. Key basic functions are represented by logic gate, logic function, flip-flop memories, optical random access memories, etc.. Research in this field is in its very early stages even if some interesting techniques have been already theoretically addressed and experimentally demonstrated. In this paper we review the state of the art for all-optical flip-flop including different approaches such as fiber based, semiconductor amplifier based or waveguide and micro-ring solutions. Best result will be highlighted in terms of transition speed, switching energy, complexity and power consumption. Finally our best results are discussed.

Charged particle sources based on photoionisation of laser cooled atoms can provide unique properties, in particular high spatial coherence and the ability to create complex three-dimensional spatial density distributions, allowing detailed measurement of the internal charged particle interactions. Cold electrons extracted from laser cooled atoms promise the spatial coherence and high current required for picosecond molecular scale imaging. Similarly, sources of cold ions provide the opportunity of ion microscopy and ion beam milling with unprecedented resolution. We use arbitrary and real-time control of the electron and ion bunch shapes to demonstrate and measure the high spatial coherence of the cold atom electron and ion source.

Portable systems are becoming the de-facto necessity of users. The efficacy of a portable system depends on the battery life, which is determined by the power consumption of the entire system. Handheld Ground Penetrating Radar (HHGPR) is a sensor used for detection of landmines buried under the surface of earth. HHGPR is a portable, compact, low power battery operated system. This system needs to be operated continuously for 8 hours on battery. So utmost care is required in designing and developing every sub-system in terms of Size, Weight and Power consumption (SWaP). As the sub system power consumption increases, weight and size of the system also increases. Typical radar consists of the sub systems like Transmitter, receiver, signal processor, data processor and Display to do distinct functionalities. Conventional Radar applications have signal processor, data processor and display realized as separate hardware. This paper describes the hardware and software design steps and challenges in realizing a custom low power (< 3W) image and data processor sub system which can do functionalities of Radar Controller, Image processor and Display processor for Handheld Ground Penetrating radar which is developed along with a signal processor on a compact single PCB to meet the SWaP constraints of a portable system. The image and data processor subsystem realised in this paper has been used in Handheld Ground Penetrating Radar (GPR) and it is developed in Electronics & Radar Development Establishment (LRDE), Defence Research & Development Organization (DRDO).