Abstract:For semiconductor spin qubits, complementary-metal-oxide-semiconductor (CMOS) technology is the ideal candidate for reliable and scalable fabrication. Making the direct leap from academic fabrication to qubits fabricated fully by industrial CMOS standards is difficult without intermediate solutions. With a flexible back-end-of-line (BEOL) new functionalities such as micromagnets or superconducting circuits can be added in a post-CMOS process to study the physics of these devices or achieve proof of concepts. O… Show more
“…[148] Electrically driven resonance was demonstrated using inter-valley SOC-mediated spin-valley coupling, [149] but this method is valid only when the Zeeman splitting and valley splitting are close to crossover. Recently, by using a post-CMOS process to add a micromagnet on top of the device, the coherent manipulation of the qubit was achieved based on the synthetic SOC, but spin relaxation time coupling is reduced to 5.2 ms. [150] An enhancement of the Rabi frequency due to spin-valley mixing was also shown.…”
Quantum computing offers the potential to revolutionize information processing by exploiting the principles of quantum mechanics. Among the diverse quantum bit (qubit) technologies, silicon‐based semiconductor spin qubits have emerged as a promising contender due to their potential scalability and compatibility with existing semiconductor technologies. In this paper, the latest developments of spin qubits in gate‐defined semiconducting nanostructures made of silicon and germanium, starting from the basic properties of electron and hole states in group‐IV semiconductors, are reviewed. Specifically, various nanostructures that exploit their unique microscopic properties for qubit implementations, elaborating on the advances and challenges in experiments, are discussed. Strategies for enhancing qubit performance, such as designing new nanostructures and identifying suitable operating points, particularly those involving the valleys of electron qubits and the heavy‐hole–light‐hole mixing of hole qubits, are also highlighted. This comprehensive review thus provides valuable insights into the current state‐of‐the‐art in semiconductor quantum computing and suggests avenues for future research.
“…[148] Electrically driven resonance was demonstrated using inter-valley SOC-mediated spin-valley coupling, [149] but this method is valid only when the Zeeman splitting and valley splitting are close to crossover. Recently, by using a post-CMOS process to add a micromagnet on top of the device, the coherent manipulation of the qubit was achieved based on the synthetic SOC, but spin relaxation time coupling is reduced to 5.2 ms. [150] An enhancement of the Rabi frequency due to spin-valley mixing was also shown.…”
Quantum computing offers the potential to revolutionize information processing by exploiting the principles of quantum mechanics. Among the diverse quantum bit (qubit) technologies, silicon‐based semiconductor spin qubits have emerged as a promising contender due to their potential scalability and compatibility with existing semiconductor technologies. In this paper, the latest developments of spin qubits in gate‐defined semiconducting nanostructures made of silicon and germanium, starting from the basic properties of electron and hole states in group‐IV semiconductors, are reviewed. Specifically, various nanostructures that exploit their unique microscopic properties for qubit implementations, elaborating on the advances and challenges in experiments, are discussed. Strategies for enhancing qubit performance, such as designing new nanostructures and identifying suitable operating points, particularly those involving the valleys of electron qubits and the heavy‐hole–light‐hole mixing of hole qubits, are also highlighted. This comprehensive review thus provides valuable insights into the current state‐of‐the‐art in semiconductor quantum computing and suggests avenues for future research.
“…Figure 1(a) presents the gate defined double quantum dot (DQD) device fabricated on an isotopically purified 28 Si epilayer (with the residual 29 Si concentration of 60 ppm). Three overlapping layers of aluminum gates [30,36] with plasma enhanced oxidation [37] to ensure electrical isolation property are used to define the QD structure and single-electron-transistor (SET) structure.…”
Section: Device and Qubit State Readoutmentioning
confidence: 99%
“…[24][25][26] When the Zeeman splitting energy is comparable to E vs , the electron spin state and valley state will mix, achieving a significantly enhanced Rabi frequency at this spinvalley hotspot. [27,28] However, the spin state relaxation rate is also enhanced at spin-valley hotspot. [20,29,30] Additionally, due to the presence of valleys, the EDSR signal of a single electron spin qubit in a QD may be more complex than that suggested by the simple two-level Hamiltonian.…”
Valley, the intrinsic feature of silicon, is an inescapable subject in silicon-based quantum computing. At the spin-valley hotspot, both Rabi frequency and state relaxation rate are significantly enhanced. With protection against charge noise, the valley degree of freedom is also conceived to encode a qubit to realize noise-resistant quantum computing. Here, based on the spin qubit composed of one or three electrons, we characterize the intrinsic properties of valley in an isotopically enriched silicon quantum dot (QD) device. For one-electron qubit, we measure two electric-dipole spin resonance (EDSR) signals which are attributed to partial occupation of two valley states. The resonance frequencies of two EDSR signals have opposite electric field dependences. Moreover, we characterize the electric field dependence of the upper valley state based on three-electron qubit experiments. The difference of electric field dependences of two valleys is 52.02 MHz/V, which is beneficial for tuning qubit frequency to meet different experimental requirements. As an extension of electrical control spin qubits, the opposite electric field dependence is crucial for qubit addressability, individual single-qubit control and two-qubit gate approaches in scalable quantum computing.
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