Can Quantum Computers Change Electron States into Anything Possible?

Industry, university and government ... build electronics and laser systems that create entanglement more efficiently and robustly. And they are experimenting with many kinds of qubits. In theory, any particle or system that obeys the rules of quantum physics, from atoms to tiny circuits to semiconductors, can act as a qubit. Each qubit has advantages and disadvantages. For example, one of the most popular qubit types uses electrically charged atoms known as ions. The quantum energy states of electrons ...

Unlike classical computers that process information using bits (0s and 1s), quantum computers employ qubits, which use the principles of quantum physics — the science of how matter and energy behave at the tiniest scales — to represent information in entirely new ways. Qubits can exist in a superposition of multiple states, meaning they can be in state 0, state 1, or a mix of the two.

The method developed by a team ... Development Award, traps one or two electrons in microscopic corrals created by applying voltages to minuscule electrodes giving them an ability to control spin orientation....

Looking at the electronic structure of the molecule—the different low-energy levels it has—that information is what we use in chemical reactions.” · These problems are especially challenging for classical computers because quantum systems are, by their nature, uncertain.

Designing new experiments in physics is a challenge for humans; therefore, computers have become a tool to expand scientists’ capabilities and to provide creative solutions. This Perspective article examines computer-inspired designs in quantum physics that led to laboratory experiments and ...

The researchers — who are based at Southern University of Science and Technology in Shenzhen, the International Quantum Academy in Shenzhen, and Hefei National Laboratory — use a system composed of four nuclear spin qubits and one electron spin qubit, and show that an arbitrary single-qubit error can be detected.

We implement example algorithms and generate the highest-fidelity three-photon Greenberger-Horne-Zeilinger states to date. The technique we use allows one to add a control operation to a black-box unitary, something that is impossible in the standard circuit model. Our experiment represents the first use of this technique to control a two-qubit operation and paves the way for larger controlled circuits to be realized efficiently. Physics of lateral triple quantum-dot molecules with controlled electron numbers.

As mentioned earlier, universal quantum computing requires the implementation of arbitrary single-qubit rotation and two-qubit entangling gates, as well as an independent local readout of all qubits. A combination of these elements serves as the building block for preparing and benchmarking arbitrary target states. However, owing to experimental limitations, not all quantum devices fulfill these requirements.

Single-electron spin qubits using enriched 28Si CVD epilayers formed on natural silicon substrates have demonstrated more than an order of magnitude improvement in coherence relative to natural silicon, leading to T2* ~ 120 μs for gate-defined MOS quantum dots (147), T2* ~ 20 μs for gate-defined Si/SiGe quantum dots (27), and T2,DD ~ 500 ms for electrons bound to phosphorus donors (26). Dynamical decoupling measurements reveal a noise spectrum consistent with 1/f noise in these studies (27), indicating that decoherence in these systems is limited by noise sources other than background nuclear spins.