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Light-Matter interface detection of the full correlations distribution of quantum many-body systems

量子多体系统全相关分布的光-物质界面检测

基本信息

批准号：
EP/L005026/1
负责人：
Gabriele De Chiara
金额：
$ 12.58万
依托单位：
Queen's University Belfast
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FL005026%2F1
关键词：
Light Matter interface detection full

项目摘要

The last fifty years have witnessed tremendous advances in science and technology with a huge impact on society and economy leading to a new information revolution in analogy with the industrial one. Although electronic devices have reached an incredible level of complexity, control and miniaturisation, information processing relies on the same classical principles enunciated by mathematicians in the 1930s (Turing, Church, von Neumann). In the 1980s, visionary ideas from theoretical physicists, including R. P. Feynman and D. Deutsch, and later from computer scientists such as P. Shor, combining concepts from quantum mechanics led to another revolution of information technology: the birth of quantum information theory. In the classical world, a bit, the smallest unit of information, can assume values 0 or 1 corresponding roughly to an electrical circuit being open or closed. In the quantum world, instead, one deals with quantum bits or qubits, embodied for example by an electron spin or a photon polarisation. These qubits can assume the two values 0 and 1 as in the classical case but they can also be prepared in a superposition of the two values simultaneously. This, apparently shocking, property has been verified in numerous experiments and is responsible for the amazing speed-up of certain tasks like integer numbers factorisation with quantum computers, i.e. devices that process qubits in analogy with traditional computers.So far quantum computers have only been realised with a small number of qubits-no more than ten-with trapped ions or neutral atoms, photons but also solid state devices. Large scale quantum computers are therefore expected to be realised only in a few decades.However special purposes quantum computers, called quantum simulators are currently being produced in laboratories working with atoms at temperatures one billionth above the absolute zero (ultracold). Such experiments aim at reproducing, with a controlled environment, the physics of hard to access quantum materials, for example a high-temperature superconductor, thus allowing scientists to probe its properties and test models and theories.A big open question for quantum simulators with ultracold atoms is how, once the sample is prepared in a quantum state, to detect its features. Several techniques are being used based on imaging through a high resolution optical microscope or on scattering of laser light off the sample. In this project we propose the use of a beam of polarised light to probe arrays of neutral atoms. As a consequence of the light-atoms interaction, the light polarisation rotates depending on the state of the atoms. Therefore the outgoing pulse of light, that can be measured, gives information about the state of the atoms.The advantage of this scheme is that one can perform the measurement without destroying the atomic samples as in other proposals. The outcomes of this project will shed light on the intimate structure of the quantum state of many qubits embodied by atoms trapped by electromagnetic fields. For this reason, it is expected to have a strong impact not only in quantum information theory, but also in atomic physics, in statistical mechanics and in the condensed matter physics. Qubits have another peculiarity compared to their classical counterpart: one can correlate the state of one qubit with that of another one in such a way that if one performs a measurement of the two qubits the outcomes always coincide. This phenomenon called entanglement is at the basis of quantum information applications like quantum teleportation. Another goal of this project is a proposal to entangle two of these ultracold atomic samples thus creating entanglement between two separated massive objects composed of hundreds of atoms. The scheme we propose can be implemented in the next generation of experiments with ultracold atoms.

在过去的五十年里，科学技术取得了巨大的进步，对社会和经济产生了巨大的影响，导致了一场与工业革命类似的新的信息革命。虽然电子设备已经达到了令人难以置信的复杂程度，控制和可编程性，但信息处理依赖于20世纪30年代数学家（图灵，丘奇，冯诺依曼）阐述的经典原理。在20世纪80年代，理论物理学家，包括R。P. Feynman和D.多伊奇，以及后来的计算机科学家如P.肖尔，将量子力学的概念结合起来，导致了信息技术的另一场革命：量子信息理论的诞生。在经典世界中，一个比特，信息的最小单位，可以假定值0或1，大致对应于电路的断开或闭合。相反，在量子世界中，人们处理量子比特或量子比特，例如通过电子自旋或光子极化来体现。这些量子位可以像经典情况一样假设两个值0和1，但它们也可以同时以两个值的叠加来制备。这一显然令人震惊的特性已经在许多实验中得到了验证，并且是量子计算机（即处理量子比特的设备，与传统计算机类似）在某些任务（如整数因式分解）中惊人加速的原因。到目前为止，量子计算机只实现了少量的量子比特-不超过10个-捕获离子或中性原子，光子，但也有固态设备。大规模的量子计算机有望在几十年内实现，然而，特殊用途的量子计算机，称为量子模拟器，目前正在实验室中生产，在绝对零度以上十亿分之一的温度下使用原子（超冷）。这些实验的目的是在受控环境下再现难以获得的量子材料（例如高温超导体）的物理特性，从而使科学家能够探测其特性并测试模型和理论。对于具有超冷原子的量子模拟器来说，一个很大的开放问题是，一旦样品在量子状态下制备，如何检测其特征。基于通过高分辨率光学显微镜成像或基于激光从样品散射的几种技术正在被使用。在这个项目中，我们提出使用一束偏振光来探测中性原子阵列。由于光与原子的相互作用，光的偏振根据原子的状态而旋转。因此，可以测量的出射光脉冲给出了关于原子状态的信息。这种方案的优点是可以在不破坏原子样品的情况下进行测量。该项目的成果将揭示许多量子比特的量子态的亲密结构，这些量子比特由被电磁场捕获的原子所体现。因此，它不仅在量子信息理论中，而且在原子物理学、统计力学和凝聚态物理学中都将产生巨大的影响。与经典量子比特相比，量子比特还有另一个特点：人们可以将一个量子比特的状态与另一个量子比特的状态相关联，如果对两个量子比特进行测量，结果总是一致的。这种被称为纠缠的现象是量子信息应用的基础，如量子隐形传态。该项目的另一个目标是将两个超冷原子样品纠缠在一起，从而在两个由数百个原子组成的分离的大质量物体之间产生纠缠。我们提出的方案可以在下一代超冷原子实验中实现。