Quantum Experiments: Study Notes

General Science July 28, 2025 6 min read

What is Quantum Physics?

Quantum physics studies the smallest things in the universe—like atoms and particles even smaller than atoms (electrons, photons, etc.). It explains how these tiny things behave in ways that seem strange compared to what we see every day.

Real-World Analogies

1. Water Molecules and Dinosaurs

Fact: The water you drink today may have been drunk by dinosaurs millions of years ago.
Analogy: Just as water molecules cycle through time and space, quantum particles can exist in different places and states, sometimes even at the same time!

2. Quantum Superposition: The Spinning Coin

Analogy: Imagine flipping a coin. While it’s spinning, it’s not just heads or tails—it’s both at once. In quantum physics, particles can exist in multiple states at the same time until measured.

3. Quantum Entanglement: The Magic Pair of Gloves

Analogy: If you put a left glove in one box and a right glove in another, and send them to opposite sides of the world, opening one box instantly tells you what’s in the other. In quantum entanglement, two particles can be linked so that what happens to one instantly affects the other, no matter how far apart they are.

4. Quantum Tunneling: The Ball Through a Wall

Analogy: Imagine rolling a ball at a wall. In the everyday world, the ball bounces back. In the quantum world, sometimes the ball “tunnels” right through the wall, appearing on the other side!

Key Quantum Experiments

1. Double-Slit Experiment

Setup: Shine a beam of light (or electrons) at a barrier with two slits, and observe the pattern on a screen behind the barrier.
Result: Instead of two lines, you see an interference pattern—like ripples in water—showing that particles act like waves.
Key Point: When you try to observe which slit the particle goes through, the interference pattern disappears. Observation changes the outcome!

2. Stern-Gerlach Experiment

Setup: Shoot silver atoms through a magnetic field.
Result: Atoms split into two distinct paths, showing that quantum particles have “spin” (like tiny magnets) that can only be up or down, not in between.

3. Quantum Eraser Experiment

Setup: A twist on the double-slit experiment. After particles pass through the slits, you can “erase” the information about which slit they went through.
Result: The interference pattern comes back if you erase the information, showing that what you know affects what happens.

Key Equations

Schrödinger Equation:
iħ ∂ψ/∂t = Ĥψ
Describes how the quantum state of a system changes over time.
Heisenberg Uncertainty Principle:
Δx × Δp ≥ ħ/2
You can’t know both the position (x) and momentum (p) of a particle exactly at the same time.
Planck’s Equation:
E = hf
Energy (E) of a photon equals Planck’s constant (h) times frequency (f).

Common Misconceptions

Misconception 1: Quantum physics only applies to tiny things.
Reality: Quantum effects can influence larger systems, especially at very low temperatures or in special materials.
Misconception 2: Particles “decide” what to do when observed.
Reality: Observation means interacting with the particle, which changes its state.
Misconception 3: Quantum entanglement allows faster-than-light communication.
Reality: Entanglement links particles, but you can’t use it to send information faster than light.
Misconception 4: Quantum mechanics is just random.
Reality: It’s probabilistic, meaning outcomes have certain probabilities, but it follows strict mathematical rules.

Recent Breakthroughs

1. Quantum Teleportation Over Long Distances

Breakthrough: In 2020, researchers in the US and China teleported quantum information over 44 kilometers of fiber optic cable, a record distance for quantum communication (Source: Science News, Dec 2020).
Significance: This could lead to ultra-secure quantum internet.

2. Quantum Supremacy

Breakthrough: In 2019, Google’s quantum computer solved a problem in 200 seconds that would take supercomputers thousands of years.
Significance: Shows quantum computers can outperform classical computers for specific tasks.

3. Time Crystals

Breakthrough: In 2021, scientists at Google and Stanford created “time crystals,” a new phase of matter that changes constantly without using energy (Source: Nature, 2021).
Significance: Could be used in future quantum computers and new technologies.

4. Quantum Sensors

Breakthrough: In 2022, quantum sensors were used to detect brain activity with extreme precision (Source: Phys.org, 2022).
Significance: May revolutionize medical imaging and diagnostics.

Latest Discoveries

Quantum Entanglement in Living Systems:
In 2023, researchers found evidence that quantum entanglement might play a role in photosynthesis in plants, helping them convert sunlight to energy more efficiently (Source: Science Advances, 2023).
Room-Temperature Superconductors:
In 2020, scientists created a material that conducts electricity with zero resistance at room temperature, but only under high pressure (Source: Nature, 2020).
Potential Impact: Could lead to lossless power grids and faster computers.

Summary Table

Experiment	What It Shows	Real-World Analogy
Double-Slit	Wave-particle duality	Water ripples
Stern-Gerlach	Quantum spin	Compass needle
Quantum Eraser	Role of information in measurement	Erasing a clue in a mystery
Quantum Teleportation	Transfer of quantum state	Faxing a secret code

Key Takeaways

Quantum physics describes a world where particles can be in many places at once, linked across space, and behave in ways that defy classical logic.
Experiments like the double-slit and quantum eraser reveal the surprising nature of reality at the smallest scales.
Recent breakthroughs are leading to new technologies like quantum computers, secure communication, and advanced sensors.
Many common ideas about quantum physics are based on misunderstandings; it’s not magic, but a set of rules that are just very different from everyday experience.