Quantum mechanics stands as one of physics’ most accurate yet puzzling theories, built on the idea that every quantum system is described by a wavefunction, a mathematical expression capturing all possible states the system can occupy. This has sparked a range of interpretations attempting to make sense of this counterintuitive behavior. The Copenhagen interpretation centers on the role of measurement, the Many-Worlds view envisions branching universes, and the de Broglie–Bohm approach describes particles guided by a hidden pilot wave. Each perspective offers a unique way of looking at reality, fueling debate while also inspiring advances in quantum computing, sensing, and communication that are shaping tomorrow’s technologies.
The Classical (Copenhagen) Interpretation
Credited to Niels Bohr, this interpretation of quantum mechanics, devised in Copenhagen, was the first attempt to understand the theoretical background of quantum mechanics. It provided a thorough mathematical framework for accurately predicting the probability of occurrence of different quantum states. The Copenhagen interpretation emphasizes that both the type of experiment and the measuring apparatus influence the eigenvalues obtained for any quantum observable, as well as the probability of their occurrence. It also introduced the key concept of complementarity; an inherent property of quantum systems that describes how certain physical attributes can only be fully understood through mutually exclusive experimental setups.
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Many Worlds or the Relative State Interpretation
The opposite of classical interpretation, the Many-worlds interpretation suggests that everything, including the observer and measuring device, is part of the quantum system, without any concept of wavefunction collapse. Rather than assuming the wavefunction collapses from a superposition into a single classical state, the Many-Worlds interpretation proposes that each measurement causes the universe to branch. In every branch, a different outcome of the measured observable is realized, so all possible results occur, but in separate, non-interacting universes. In this interpretation, the Schrödinger’s Cat paradox is easily resolved, with the cat being alive in one universe while dead in another universe branching from the main quantum universe.
De Broglie-Bohm pilot-wave interpretation
De Broglie’s pilot-wave theory describes a quantum system as point particles with definite positions moving along well-defined paths. These trajectories are guided entirely by the wavefunction, which dictates the particles’ velocities at every moment.
Since the position of particles is fixed, the velocity field fully controls the path of particles. In this way, the particles are ‘guided’ by the wavefunction, which gives the interpretation its name.1
Unlike other interpretations, it is fully deterministic. The apparent randomness of quantum mechanics emerges from our ignorance of the particles’ exact initial positions. This makes the theory conceptually closer to classical mechanics, while still reproducing all the predictions of standard quantum theory.
Although each interpretation offers its own strengths and faces certain limitations, none can fully account for every interaction at the quantum level. The meaning of quantum principles, especially foundational concepts like the wavefunction, remains an active area of research and debate.
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Real World Applications
Quantum computing harnesses qubits, which use the principle of quantum superposition to enable faster computations. In superposition, a qubit can exist in a combination of both its basis states, |0⟩ and |1⟩, at the same time. This means a single qubit can represent and process multiple states of information simultaneously, something classical computers cannot achieve with ordinary bits.
Microsoft uses quantum-based processors that use quantum superposition to enable parallelism in computation. The classical bits can only perform one computation at a time, depending on their state, while the quantum processors use the superposition principle to enable the computer to perform multiple computations in tandem by processing the multiple quantum states of a qubit.2
Similarly, quantum entanglement involving a shared quantum state between two systems or particles separated by a large distance has proven to be revolutionary. These systems can be described by a single wavefunction, and any action on one system affects the other.
The transfer of quantum states between two entangled far-away systems has pushed us into a new era of quantum teleportation. Furthermore, it has been critical in maturing the next-generation of quantum error correction technology, which is key for protection against quantum decoherence. The creation and manipulation of entangled quantum states allows not only for faster computation, but also for the detection of errors using novel algorithms not programmable using classical computers.3
Not only this, but many startups are focusing on scaling quantum sensors for real-world industrial applications. The spatial resolution and superior sensitivity of quantum sensors make them a viable choice for many sectors, especially the biomedical sector, ensuring the safety of human health by improving neural tissue imaging and single-cell spectroscopy.4
Future Perspective
Quantum computing and other technologies are being researched readily throughout the world. Although AI has advanced rapidly, researchers are now exploring Quantum Neural Networks (QNNs), a framework that blends the parallel processing and speed of quantum systems with the learning capabilities of artificial intelligence.5
Similarly, several useful innovations are being researched to improve the quantum state tomography field, with experts utilizing quantum machine learning to develop innovative ways that not only improve efficiency but also lead to much superior fidelity with fewer measurement samples.6
Additionally, the emergence of various types of hybrid quantum systems, like Magnon-skyrmion hybrid quantum systems, is providing efficient architectures for novel smart cities, enhancing security in quantum cryptography, and allowing for control of spin-photos in novel quantum systems on chip infrastructures.7, 8
There is no doubt that quantum technologies are evolving rapidly, and with significant progress being made in understanding fundamental concepts like wavefunction collapse, quantum mechanics principles will soon be implemented and scaled successfully to power industries throughout the world.
Further Reading
- Struyve, W. (2005). The de Broglie-Bohm pilot-wave interpretation of quantum theory. arXiv preprint quant-ph/0506243. Available at: https://doi.org/10.48550/arXiv.quant-ph/0506243
- Microsoft. (2025). Explore Quantum: Superposition. [Online]. Available at: https://quantum.microsoft.com/en-us/insights/education/concepts/superposition [Accessed on: July 22, 2025].
- Microsoft. (2025). Explore Quantum: Entanglement. [Online]. Available at: https://quantum.microsoft.com/en-us/insights/education/concepts/entanglement [Accessed on: July 22, 2025].
- Aslam, N. et al. (2023). Quantum sensors for biomedical applications. Nat Rev Phys 5. 157–169. Available at: https://doi.org/10.1038/s42254-023-00558-3
- Yu, S. et. al. (2024). Shedding Light on the Future: Exploring Quantum Neural Networks through Optics. Advanced Quantum Technologies. 2400074. Available at: https://doi.org/10.1002/qute.202400074
- Innan, N. et al. (2024). Quantum state tomography using quantum machine learning. Quantum Mach. Intell. 6, 28. Available at: https://doi.org/10.1007/s42484-024-00162-3
- Santa Barletta, V. et. al. (2024). Hybrid quantum architecture for smart city security. Journal of Systems and Software. 217. 112161. Available at: https://doi.org/10.1016/j.jss.2024.112161
- Clark, G. et. al. (2024). Nanoelectromechanical control of spin–photon interfaces in a hybrid quantum system on chip. Nano Letters, 24(4), 1316-1323. Available at: https://doi.org/10.1021/acs.nanolett.3c04301
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