Towards molecular bits: molecules that can represent binary information

迈向分子比特：可以表示二进制信息的分子

• 批准号: EP/E052142/1
• 负责人: Christopher Adams
• 金额: $ 26.14万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2007
• 资助国家: 英国
• 起止时间: 2007 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FE052142%2F1
• 关键词: Towards; molecular; bits; molecules; represent

When the first commercially successful microprocessor was launched in 1974 it contained roughly 6000 transistors on one silicon chip, each transistor representing one bit of binary information. Thirty-two years later, the Pentium 4 has 42 million transistors on a chip, giving an idea of how miniaturisation has progressed in that time. However, transistors are not going to become very much smaller because of two problems. Firstly, as the size of a transistor decreases, it becomes more difficult to make it turn on and off cleanly (a transistor is just a switch that uses on and off states to represent 0 and 1). Secondly, transistors generate heat, and transistor densities are becoming so high that removing that heat and stopping the chips from melting is a real challenge.The aim of this proposed research is to synthesise some chemical compounds that could be used to replace transistors in electronic devices, using a new way of representing and manipulating binary information called the Quantum-dot Cellular Automata (QCA) paradigm. A QCA cell consists of four metallic dots arranged in a square, each dot being able to accommodate an electrical charge. Electrically charging the dots at two of the opposite corners of a cell can be used to encode 0, while charging the other two dots represents 1. Where more than one QCA cell is present, the arrangement of the charged dots within one cell affects that in neighbouring cells. Because like charges repel each other, dots that are next to each other tend to have opposite charges, which means that where two cells are side-by-side the second will have the same value (0 or 1) as the first. Conversely, two cells sharing a corner will adopt opposite values. This second kind of arrangement, where a value of the input cell of 1 is converted to an output cell value of 0, is equivalent to a NOT gate in conventional electronics. Other kinds of logic gate can be mimicked by other arrangements of cells, and so the correct arrangement of cells could function as a computer.It has been shown that an arrangement of QCA cells with metallic nanoparticles about 50 nm in size at the corners can work as a logic gate at milliKelvin temperatures, and whilst this is too cold for general purpose computing it is predicted that if the metallic components can be shrunk to about 2 nm then they will work at room temperature. Two nanometres is about the same size as a single molecule, so if we can build a molecule that contains an array of four centres, each of which can be switched 'on' or 'off' as described above, then we might be able to use them in computing.In chemical terms, switching each 'dot' on or off is simply a redox process - adding or removing an electron - so each corner needs to be made from something that is stable in more than one oxidation state. What is proposed is to join four such entities together with some chemical scaffolding to form molecular QCA cells, and then investigate their behaviour to see whether they would work as desired.

当第一个商业上成功的微处理器于1974年推出时，它在一个硅芯片上包含大约6000个晶体管，每个晶体管代表一位二进制信息。32年后，奔腾4在一个芯片上有4200万个晶体管，这让人们了解到当时的计算机化是如何发展的。然而，由于两个问题，晶体管不会变得很小。首先，随着晶体管尺寸的减小，使其干净地打开和关闭变得更加困难（晶体管只是一个开关，使用开和关状态来表示0和1）。第二，晶体管会产生热量，而晶体管的密度越来越高，去除热量并阻止芯片熔化是一个真实的挑战。这项研究的目的是合成一些化合物，这些化合物可以用来取代电子设备中的晶体管，使用一种新的表示和操纵二进制信息的方法，称为量子点元胞自动机（QCA）范式。QCA电池由四个排列成正方形的金属点组成，每个点都能容纳电荷。在一个单元的两个相对的角上对点充电可以用来编码0，而对另外两个点充电表示1。在存在多于一个QCA单元的情况下，一个单元内的带电点的布置影响相邻单元中的带电点的布置。因为相同的电荷互相排斥，所以相邻的点往往具有相反的电荷，这意味着当两个单元并排时，第二个单元将具有与第一个单元相同的值（0或1）。相反，共享一个角的两个单元将采用相反的值。这种第二种布置，其中输入单元的值1被转换为输出单元值0，相当于传统电子设备中的非门。其他类型的逻辑门可以通过其他排列的单元来模仿，因此正确的单元排列可以起到计算机的作用。已经表明，在角落处具有大约50 nm大小的金属纳米颗粒的QCA单元的排列可以在毫开尔文温度下作为逻辑门工作，虽然这对于通用计算来说太冷了，但是预计如果金属部件可以收缩到大约2nm，那么它们将在室温下工作。两纳米的大小相当于一个分子的大小，因此，如果我们能够构建一个包含四个中心的分子阵列，每个中心都可以如上所述地“打开”或“关闭”，那么我们就可以在计算中使用它们。打开或关闭每个"点"仅仅是一个氧化还原过程-添加或移除一个电子，所以每个角都需要由在一种以上氧化态下稳定的物质制成。我们提出的是将四个这样的实体与一些化学支架连接在一起，形成分子QCA细胞，然后研究它们的行为，看看它们是否会按预期工作。