Author: haroonkhan
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LIGHT AS AN ELECTROMAGNETIC WAVE
Later, in the 1860s, Scottish physicist James Clerk Maxwell identified light as an electromagnetic wave. Maxwell had derived a wave form of the electric and magnetic equations, revealing a wave-like nature of electric and magnetic fields that vary with time. Maxwell figured out that an electric field that varies along space generates a magnetic field…
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THE FINAL NAIL IN THE COFFIN FOR NEWTON’S THEORY OF LIGHT
Diffraction, reflection, and color are also explained by Young’s wave theory. However, interference is the calling card of waves, so Young’s experiments convinced many in the early 1800s that light is indeed a wave. In spite of this, Newton’s reputation was so strong, that his particle model of light retained adherents until 1850, when French…
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AUTOMATIC SCANNING OF INTERFERENCE PATTERNS
Accurately measuring interference patterns from projections on a screen is rather tedious. However, you can build a simple device that makes it possible to display interference patterns on an oscilloscope, making it easy to measure not only the distance between fringes, but also their amplitude. As shown in Figure 5, the idea is to use a…
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YOUNG’S INTERFERENCE OF LIGHT
Around 1801, Thomas Young discovered interference of light. This phenomenon is only possible with waves, providing conclusive evidence that light is a wave. In Young’s experiments, light sent through two separate slits results in a pattern that is very similar to the one produced by the interference of water waves shown in Figure 2. Figure 2 Water…
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LIGHT CONSISTS OF PARTICLES
In 1704, Sir Isaac Newton proposed that light consists of little particles of mass. In his view, this could explain reflection, because an elastic, frictionless ball bounces off a smooth surface just like light bounces off a mirror—that is, the angle of incidence equals the angle of reflection. Remember that Newton was very interested in…
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Introduction
Before we get into quantum physics, let’s understand the classical view of light. As early as 100 C.E., Ptolemy—a Roman citizen of Egypt—studied the properties of light, including reflection, refraction, and color. His work is considered the foundation of the field of optics. Ptolemy was intrigued by the way that light bends as it passes…
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Quantum Teleportation
Star Trek introduced us to the fantastic notion of teleporting humans from one place to another, such as from the Starship Enterprise to planets beneath. Doing so was quite convenient, and eliminated the need for expensive landings and takeoffs. It certainly would make life more convenient if we could avoid the morning commute and just teleport…
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Quantum Cryptography
Sharing secrets is as old as humanity, and evidence of coded messages has been traced back to ancient civilizations. Cryptography is a technique intended to code a message into an incomprehensible string of characters that can only be decoded by the intended recipient. And, just as the lock on your front door can only be…
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Building a Quantum Computer
While this all sounds great in theory, building a useful quantum computer turns out to be pretty tricky. There are two challenges in particular that will need to be overcome before qubits are actually applied on our desktops or in our mobile phones. When performing our operations, we introduce well-characterized perturbations to the qubits, which…
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Quantum Computation
Now that we understand how to set up a quantum computer, at least in theory, how can it be used to perform actual calculations? Just like in the classical case, the process boils down to three steps. First, our set of qubits must be prepared, or initialized, into a starting state. Then, we would have…