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（左起）研究生苗凯文（Kevin Miao），克瑞斯 安德森（Chris Anderson）和亚历山大 薄若纱（Alexandre Bourassa）在Pritzker分子工程学院监测量子实验。
经过数十年的小型化，我们用于计算机和现代技术的电子组件现已开始达到基本极限。面对这一挑战，世界各地的工程师和科学家都在转向一种全新的范例：量子信息技术。
通常认为，量子技术利用了在原子级上控制粒子的奇怪规则，通常认为它过于精致，无法与我们每天在手机，笔记本电脑和汽车中使用的电子设备共存。但是，芝加哥大学普利兹克分子工程学院的科学家宣布了一项重大突破：量子态可以集成和控制在由碳化硅制成的常用电子设备中。
首席研究员David Awschalom说：“在商业电子产品中创建和控制高性能量子比特的能力令人惊讶，” UChicago分子工程的Liew家族教授，量子技术的先驱David Awschalom说。 “这些发现改变了我们对开发量子技术的思考方式，也许我们可以找到一种方法来利用当今的电子技术来制造量子设备。”
在《科学》与《科学进展》上发表的两篇论文中，Awschalom的小组证明了它们可以电控制嵌入碳化硅中的量子态。与科学家通常需要用于量子实验的异质材料（例如超导金属，悬浮原子或钻石）相比，这一突破可能提供了一种更轻松地设计和构建量子电子学的方法。
碳化硅中的这些量子态具有发射波长接近电信频段的光的单个粒子的额外好处。 “这使它们非常适合通过同一光纤网络进行长距离传输，该光纤网络已经在全球范围内传输了90％的所有国际数据，”阿贡国家实验室的高级科学家，芝加哥量子交易所主管Awschalom说。
此外，与现有电子设备结合使用时，这些轻质颗粒可以获得令人兴奋的新特性。例如，在《科学进展》的论文中，该团队能够创建Awschalom所谓的“量子FM收音机”；就像将音乐传输到您的汽车收音机一样，量子信息可以在非常长的距离内发送。
该论文的第一作者，研究生凯文·苗（Kevin Miao）说：“所有理论都表明，为了在一种材料中实现良好的量子控制，它应该是纯净的且没有波动的场。” “我们的结果表明，通过适当的设计，设备不仅可以减轻这些杂质，还可以创建以前无法实现的其他控制形式。”
在《科学》杂志的论文中，他们描述了解决量子技术中一个非常普遍的问题的第二项突破：噪声。
该论文的共同第一作者，研究生克里斯·安德森说：“杂质在所有半导体器件中都很普遍，在量子水平上，这些杂质会通过创建嘈杂的电环境来扰乱量子信息。” “对于量子技术来说，这是一个几乎普遍的问题。”
但是，通过使用电子学的基本要素之一，即二极管，电子的单向开关，研究小组发现了另一个出乎意料的结果：量子信号突然变得无噪声并且几乎完全稳定。
“在我们的实验中，我们需要使用激光，不幸的是，激光将周围的电子束缚起来。这就像是带有电子音乐椅的游戏；当灯光熄灭时，一切都停止了，但是结构有所不同。”论文的另一位共同第一作者，研究生亚历山德拉·波拉萨（Alexandre Bourassa）说。 “问题在于电子的这种随机配置会影响我们的量子态。但是我们发现，施加电场会将电子从系统中移出并使它更加稳定。”
通过将量子力学的奇异物理学与发达的经典半导体技术相结合，Awschalom及其团队正在为即将到来的量子技术革命铺平道路。
Awschalom说：“这项工作使我们向能够在全球光纤网络中存储和分布量子信息的系统的实现迈进了一步。” “这样的量子网络将带来一类新颖的技术，这些技术可以创建无法破解的通信通道，单电子态的隐形传送以及量子互联网的实现。”
为了进行研究，该团队使用了芝加哥材料研究中心和普利兹克纳米制造工厂。 Awschalom还与芝加哥大学的Polsky创业与创新中心合作，以推动这些发现。
引用文献：
“集成在可扩展半导体器件中的单自旋的电光控制”，Science，Anderson和Bourassa等，2019年12月6日。
“具有碳化硅中自旋的电驱动光学干涉仪。”《科学进展》，苗等人，2019年11月22日。
资金来源：国家科学基金会，国防部，空军科学研究所，海军研究处，国防高级研究计划局，日本科学促进会，瑞典能源署和瑞典研究理事会，卡尔·Tryggers科学研究基金会，克努特和爱丽丝·沃伦伯格基金会。
UChicago team discovers innovative way to tune quantum signals
After decades of miniaturization, the electronic components we’ve relied on for computers and modern technologies are now starting to reach fundamental limits. Faced with this challenge, engineers and scientists around the world are turning toward a radically new paradigm: quantum information technologies.
Quantum technology, which harnesses the strange rules that govern particles at the atomic level, is normally thought of as much too delicate to coexist with the electronics we use every day in phones, laptops and cars. However, scientists with the University of Chicago’s Pritzker School of Molecular Engineering announced a significant breakthrough: Quantum states can be integrated and controlled in commonly used electronic devices made from silicon carbide.
“The ability to create and control high-performance quantum bits in commercial electronics was a surprise,” said lead investigator David Awschalom, the Liew Family Professor in Molecular Engineering at UChicago and a pioneer in quantum technology. “These discoveries have changed the way we think about developing quantum technologies—perhaps we can find a way to use today’s electronics to build quantum devices.”
Prof. David Awschalom
In two papers published in Science and Science Advances, Awschalom’s group demonstrated they could electrically control quantum states embedded in silicon carbide. The breakthrough could offer a means to more easily design and build quantum electronics—in contrast to using exotic materials scientists usually need to use for quantum experiments, such as superconducting metals, levitated atoms or diamonds.
These quantum states in silicon carbide have the added benefit of emitting single particles of light with a wavelength near the telecommunications band. “This makes them well suited to long-distance transmission through the same fiber-optic network that already transports 90% of all international data worldwide,” said Awschalom, senior scientist at Argonne National Laboratory and director of the Chicago Quantum Exchange.
Moreover, these light particles can gain exciting new properties when combined with existing electronics. For example, in the Science Advances paper, the team was able to create what Awschalom called a “quantum FM radio;” in the same way music is transmitted to your car radio, quantum information can be sent over extremely long distances.
“All the theory suggests that in order to achieve good quantum control in a material, it should be pure and free of fluctuating fields,” said graduate student Kevin Miao, first author on the paper. “Our results suggest that with proper design, a device can not only mitigate those impurities, but also create additional forms of control that previously were not possible.”
—David Awschalom, Liew Family Professor in Molecular Engineering—David Awschalom, Liew Family Professor in Molecular Engineering —David Awschalom, Liew Family Professor in Molecular Engineering
In the Science paper, they describe a second breakthrough that addresses a very common problem in quantum technology: noise.
“Impurities are common in all semiconductor devices, and at the quantum level, these impurities can scramble the quantum information by creating a noisy electrical environment,” said graduate student Chris Anderson, a co-first author on the paper. “This is a near-universal problem for quantum technologies.”
But, by using one of the basic elements of electronics—the diode, a one-way switch for electrons—the team discovered another unexpected result: The quantum signal suddenly became free of noise and was almost perfectly stable.
“In our experiments we need to use lasers, which unfortunately jostle the electrons around. It’s like a game of musical chairs with electrons; when the light goes out everything stops, but in a different configuration,” said graduate student Alexandre Bourassa, the other co-first author on the paper. “The problem is that this random configuration of electrons affects our quantum state. But we found that applying electric fields removes the electrons from the system and makes it much more stable.”
By integrating the strange physics of quantum mechanics with well-developed classical semiconductor technology, Awschalom and his group are paving the way for the coming quantum technology revolution.
“This work brings us one step closer to the realization of systems capable of storing and distributing quantum information across the world’s fiber-optic networks,” Awschalom said. “Such quantum networks would bring about a novel class of technologies allowing for the creation of unhackable communication channels, the teleportation of single electron states and the realization of a quantum internet.”
For its research, the team used the Chicago Materials Research Center and the Pritzker Nanofabrication Facility. Awschalom is also working with the Polsky Center for Entrepreneurship and Innovation at the University of Chicago to advance these discoveries.
Citations:
- “Electrical and optical control of single spins integrated in scalable semiconductor devices.” Science, Anderson and Bourassa et al, Dec. 6, 2019.
- “Electrically driven optical interferometry with spins in silicon carbide.” Science Advances, Miao et al, Nov. 22, 2019.
Funding: National Science Foundation, Department of Defense, Air Force Office of Scientific Research, Office of Naval Research, Defense Advanced Research Projects Agency, Japan Society for the Promotion of Science, Swedish Energy Agency and Swedish Research Council, Carl Tryggers Foundation for Scientific Research, Knut and Alice Wallenberg Foundation.
David Awschalom Talks to PBS News Hour About the Race to Develop Quantum Technology
量子竞赛，中国领先？