TINY DIGITAL CLOCK FREE

Moreover, the superposition would be spread evenly across all possible energies: if you measured the clock’s energy, your probability of obtaining one possible outcome would equal your probability of obtaining any other possible outcome. So a quantum system with a well-defined time would be in a superposition of all possible energies. Analogous to the particle’s well-defined position is an ideal quantum clock’s well-defined time the clock would not be in a superposition of many times.īut time and energy participate in an uncertainty relation similarly to position and momentum. If you measure the momentum, your detector can read any positive number, any negative number or zero. If a quantum particle has a well-defined position, the particle doesn’t have a well-defined momentum in quantum lingo, the particle is in a superposition of all possible momenta. But quantum position and momentum participate in an uncertainty relation. How could an observable not have a well-defined value? After all, you have a well-defined energy, position, and momentum. An ideal quantum clock’s time observable has a well-defined value. Example observables include energy, position and momentum. Observable is the physics name for a measurable property of a quantum system. Pauli pointed out that an ideal quantum clock has a time “observable”. He homed in on simple, yet fundamental concepts – and what is time, if not fundamental? Pauli’s interests extended from quantum physics to psychology and philosophy, and his name is now tied to the Pauli exclusion principle that governs how electrons organise in atoms. Quantum physics pioneer Wolfgang Pauli spent time in the 1920s thinking about quantum clocks, among many other things. The controller that measures the atoms’ energy isn’t quantum, so an atomic clock is not the only clock we’ll need for the quantum steampunk age. So we measure a second by waiting for the laser light to oscillate a certain number of times. The time between oscillations is a calculable fraction of a second, which is defined in terms of the energy that the atoms can absorb. In addition to consisting of particles, the light has wave-like properties and so, in a sense, oscillates up and down. If many atoms have, then the laser’s light consists of particles with just the right amount of energy – an amount calculable with quantum theory. A laser shines on the atoms, and an external controller measures how many atoms have, so to speak, eaten crisp packets from the laser. An atomic clock contains atoms that can absorb only certain amounts of energy in discrete packets – like someone who can eat one packet of crisps but not half a packet. NIST’s clock was an actual atomic clock – a quantum clock, but one whose controller didn’t exist entirely within the quantum realm. Every day, the clock received radio signals from a Colorado outpost of the National Institute of Standards and Technology (NIST), synchronising it with a highly accurate clock operated by NIST. My grandparents bought such an “atomic clock” and hung it in their kitchen, but theirs would have been more accurately called a “radio-controlled clock”.

The question is, can we build such a quantum clock that would do the job?īefore we dive in, I should clarify that an autonomous quantum clock is not the same as the so-called atomic clocks that you can buy in stores. The more a quantum drone interacted with ordinary devices, the more its entanglement could dissipate.

For instance, quantum technologies benefit from entanglement, strong correlations that sync quantum particles. Such autonomous machines would have to carry their own clocks and those clocks would have to be quantum too to prevent the machines from losing their quantum character.

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Giving our imaginations free rein, we might envision tiny quantum drones that can tinker with or deliver molecules. External classical control systems keep time for today’s quantum computers, but a control system that could operate entirely within the quantum realm would open up new possibilities. A basic part of performing any computation is executing certain tasks at certain times. And just as clocks govern us, they govern quantum devices. Sign up for Lost in Space-Time here.Ĭlocks regulate our lives, dictating when we sleep and wake, whether we catch our flights home and who wins a fortune on Wall Street. Each month, we hand over the keyboard to a physicist or two to tell you about fascinating ideas from their corner of the universe. The following is an extract from our Lost in Space-Time newsletter. Credit: Quality Stock / Alamy Stock Photo

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