As an AI language model, I can provide an overview of some significant advancements in the field of quantum computing in 2021. Here is a list of 10 notable developments:

1. Google’s Quantum Supremacy: In March 2021, Google announced the achievement of “quantum supremacy.” Their quantum computer, named Sycamore, successfully solved a calculation in just 200 seconds, which would take traditional supercomputers thousands of years.

2. IonQ’s Commercial Quantum Computer: IonQ unveiled its 32-qubit quantum computer, capable of performing complex computations. Its outstanding coherence times and negligible error rates make it commercially attractive.

3. IBM’s Quantum Roadmap: IBM introduced its “IBM Quantum Roadmap” in May 2021, outlining its plans to build increasingly larger and more capable quantum systems. This roadmap includes the development of a 1,121-qubit system by 2023.

4. Honeywell’s Commercial Quantum Computer: Honeywell released its quantum computer, the System Model H1, which features ultra-low quantum volume, a measure of computational capability. It aims to provide increased access to quantum computing through cloud services.

5. Majorana Fermions: Microsoft’s research team demonstrated the existence of elusive particles called Majorana fermions, offering potential building blocks for fault-tolerant quantum bits or qubits.

6. Quantum Error Correction Advancements: Scientists made progress in the field of quantum error correction, a critical aspect of quantum computing. They developed new methods and codes to detect and mitigate errors that occur during quantum operations.

7. Quantum Machine Learning: Researchers explored the intersection of machine learning and quantum computing. Several experiments showcased the potential of combining the two fields to enhance optimization algorithms and data analysis.

8. Topological Quantum Computing: Microsoft deployed more stable qubits based on topological properties. These robust qubits have the potential to simplify error correction, making large-scale quantum computers more feasible.

9. Quantum Communication and Encryption: Researchers made strides in quantum communication and secure quantum encryption. Techniques like quantum key distribution (QKD) advanced, which could pave the way for secure communication networks.

10. Quantum Simulations: Improvements in simulating quantum systems using quantum computers occurred, enabling scientists to gain deeper insights into problems related to material science, chemistry, and particle physics.

It’s important to note that these advancements are not exhaustive, and the field of quantum computing is rapidly evolving with ongoing developments globally.