工程师们刚刚用人工原子制造了一个非常稳定的量子硅芯片

工程师们刚刚用人工原子制造了一个非常稳定的量子硅芯片

Newly created artificial atoms on a silicon chip could become the new basis for quantum computing.

在硅片上新创造的人工原子可能成为量子计算的新基础。

Engineers in Australia have found a way to make these artificial atoms more stable, which in turn could produce more consistent quantum bits, or qubits - the basic units of information in a quantum system.

澳大利亚的工程师们找到了一种方法，可以使这些人造原子更加稳定，从而产生更加一致的量子比特，或称量子位——量子系统中的基本信息单位。

The research builds on previous work by the team, wherein they produced the very first qubits on a silicon chip, which could process information with over 99 percent accuracy. Now, they have found a way to minimise the error rate caused by imperfections in the silicon.

这项研究建立在该团队之前的工作基础上，他们在硅片上产生了第一个量子位，其处理信息的准确率超过99%。现在，他们找到了一种方法，可以最大限度地降低由硅缺陷引起的错误率。

What really excites us about our latest research is that artificial atoms with a higher number of electrons turn out to be much more robust qubits than previously thought possible, meaning they can be reliably used for calculations in quantum computers, said quantum engineer Andrew Dzurak of the University of New South Wales (UNSW) in Australia.

大利亚新南威尔士大学（UNSW）的量子工程师安德鲁·祖拉克（Andrew Dzurak）说：“我们最新的研究真正让我们兴奋的是，电子数量更高的人造原子比先前认为的可能要强大得多，这意味着它们可以可靠地用于量子计算机的计算。”。

This is significant because qubits based on just one electron can be very unreliable.

“这很重要，因为仅仅基于一个电子的量子位可能非常不可靠。”

In a real atom, electrons whizz in three dimensions around a nucleus. These three-dimensional orbits are called electron shells, and elements can have different numbers of electrons.

在真实的原子中，电子绕着原子核作三维运动。这些三维轨道被称为电子壳层，元素可以有不同数量的电子。

Artificial atoms - also known as quantum dots - are nanoscale semiconducting crystals with a space that can trap electrons, and confine their movement in three dimensions, holding them in place with electric fields.

人工原子（也称为量子点）是一种纳米级半导体晶体，其空间可以捕获电子，并将其运动限制在三维空间内，通过电场将其固定在适当的位置。

The team created their atoms using a metal surface gate electrode to apply voltage to the silicon, attracting spare electrons from the silicon into the quantum dot.

研究小组用一个金属表面栅电极来给硅施加电压，将硅中的多余电子吸引到量子点中，从而创造出原子。

In a real atom, you have a positive charge in the middle, being the nucleus, and then the negatively charged electrons are held around it in three-dimensional orbits, explained solid state physicist Andre Saraiva of UNSW.

新南威尔士大学的固体物理学家安德烈·萨拉瓦解释说:“在真实的原子中，正电荷在原子核的中间，然后带负电荷的电子在三维轨道中围绕原子核运动。”

In our case, rather than the positive nucleus, the positive charge comes from the gate electrode which is separated from the silicon by an insulating barrier of silicon oxide, and then the electrons are suspended underneath it, each orbiting around the centre of the quantum dot. But rather than forming a sphere, they are arranged flat, in a disc.

“在我们的例子中，正电荷不是来自带正电的原子核，而是来自栅电极，栅电极被氧化硅的绝缘屏障从硅中分离出来，然后电子悬浮在栅电极下，每个电子都绕着量子点的中心旋转。但它们不是形成一个球体，而是平展地排列在一个圆盘里。”

Hydrogen, lithium and sodium are elements that can have just one electron in their electron shell. This is the model used for quantum computing. When the team creates artificial atoms equivalent to hydrogen, lithium and sodium, they can use that single electron as a qubit, the quantum version of a binary bit.

氢、锂和钠都是电子壳层中只有一个电子的元素。这是用于量子计算的模型。当这个团队创造出相当于氢、锂和钠的人工原子时，他们就可以用那个电子作为量子位元，也就是二进制位的量子版本。

However, unlike binary bits, which process information in one of two states (1 or 0), a qubit can be in the state of a 1, a 0, or both simultaneously - a state called superposition - based on their spin states. This means they can perform parallel computations, rather than do them consecutively, making them a much more powerful computing tool.

然而，与二进制位不同的是，二进制位以两种状态(1或0)之一处理信息，量子位可以同时处于1、0或两者的状态——一种称为叠加的状态——基于它们的自旋状态。这意味着它们可以执行并行计算，而不是连续执行，这使它们成为更强大的计算工具。

This is what the team demonstrated previously, but the system wasn't perfect.

这是该团队之前展示的，但是这个系统并不完美。

Up until now, imperfections in silicon devices at the atomic level have disrupted the way qubits behave, leading to unreliable operation and errors, said UNSW quantum engineer Ross Leon.

新南威尔士大学的量子工程师罗斯·利昂说:“到目前为止，原子水平上的硅器件的缺陷已经扰乱了量子位元的行为方式，导致了不可靠的操作和错误。”

So, the team turned up the voltage on their gate electrode, which drew in more electrons; these electrons, in turn, mimic heavier atoms, which have multiple electron shells. In the artificial atoms, just as in real atoms, these shells are predictable and well organised.

因此，研究小组提高了栅极上的电压，从而吸引了更多的电子;这些电子，反过来，模仿更重的原子，有多个电子壳层。在人造原子中，就像在真实原子中一样，这些壳层是可预测的，而且组织良好。

When the electrons in either a real atom or our artificial atoms form a complete shell, they align their poles in opposite directions so that the total spin of the system is zero, making them useless as a qubit. But when we add one more electron to start a new shell, this extra electron has a spin that we can now use as a qubit again, Dzurak said.

“当一个真正的原子或人造原子中的电子形成一个完整的壳层时，它们将它们的极向相反的方向排列，因此系统的总自旋为零，使得它们作为一个量子位毫无用处。”但是当我们再增加一个电子来开始一个新的壳层时，这个额外的电子就有了一个自旋，我们现在又可以把它用作量子位元了，”Dzurak说。

This new set-up also appears to compensate for the errors introduced by atomic-scale imperfections in the silicon chip.

这种新的装置似乎也弥补了硅片原子尺度上的缺陷所带来的误差。

Our new work shows that we can control the spin of electrons in the outer shells of these artificial atoms to give us reliable and stable qubits, said Dzurak.

“我们的新研究表明，我们可以控制这些人造原子外层电子的自旋，从而得到可靠而稳定的量子位。”祖拉克说。

This is really important because it means we can now work with much less fragile qubits. One electron is a very fragile thing. However an artificial atom with 5 electrons, or 13 electrons, is much more robust.

“这真的很重要，因为这意味着我们现在可以用更少的脆弱量子位来工作。一个电子是非常脆弱的。然而，一个拥有5个或13个电子的人工原子要健壮得多。”

The research has been published in Nature Communications.

这项研究发表在《自然通讯》杂志上。