Commentary

The search for dark matter gets a speed boost from quantum technology

Anonymous — Wed, 10 Feb 2021 17:26:38 +0000

The search for dark matter gets a speed boost from quantum technology Anonymous (not verified) Wed, 02/10/2021 - 10:26

Benjamin Brubaker

Quantum squeezing alone isn’t enough to scan through every possible axion frequency in a reasonable time

Nearly a century after dark matter was first proposed to explain the motion of galaxy clusters, physicists still have no idea what it’s made of.

Researchers around the world have built dozens of detectors in hopes of discovering dark matter. As a graduate student, I helped design and operate one of these detectors, aptly named HAYSTAC. But despite decades of experimental effort, scientists have yet to identify the dark matter particle.

At the top of the page: Dark matter can be inferred from an assortment of physical clues in the universe. NASA. Above: The HAYSTAC detector is searching for the axion, one of the hypothetical particles that could make up dark matter. Kelly Backes, CC BY-ND

Now, the search for dark matter has received an unlikely assist from technology used in quantum computing research. In a new paper published in the journal Nature, my colleagues on the HAYSTAC team and I describe how we used a bit of quantum trickery to double the rate at which our detector can search for dark matter. Our result adds a much-needed speed boost to the hunt for this mysterious particle.

Scanning for a dark matter signal

Special superconducting circuits used for quantum computing can help detectors sift through noise that might be hiding an axion signal. Kelly Backes, CC BY-ND

There is compelling evidence from astrophysics and cosmology that an unknown substance called dark matter constitutes more than 80% of the matter in the universe. Theoretical physicists have proposed dozens of new fundamental particles that could explain dark matter. But to determine which – if any – of these theories is correct, researchers need to build different detectors to test each one.

One prominent theory proposes that dark matter is made of as-yet hypothetical particles called axions that collectively behave like an invisible wave oscillating at a very specific frequency through the cosmos. Axion detectors – including HAYSTAC – work something like radio receivers, but instead of converting radio waves to sound waves, they aim to convert axion waves into electromagnetic waves. Specifically, axion detectors measure two quantities called electromagnetic field quadratures. These quadratures are two distinct kinds of oscillation in the electromagnetic wave that would be produced if axions exist.

Cryogenic cooling helps reduce noise, but by squeezing quantum noise, the HAYSTAC detector can search for an axion signal even faster. Kelly Backes, CC BY-ND

The main challenge in the search for axions is that nobody knows the frequency of the hypothetical axion wave. Imagine you’re in an unfamiliar city searching for a particular radio station by working your way through the FM band one frequency at a time. Axion hunters do much the same thing: They tune their detectors over a wide range of frequencies in discrete steps. Each step can cover only a very small range of possible axion frequencies. This small range is the bandwidth of the detector.

Tuning a radio typically involves pausing for a few seconds at each step to see if you’ve found the station you’re looking for. That’s harder if the signal is weak and there’s a lot of static. An axion signal – in even the most sensitive detectors – would be extraordinarily faint compared with static from random electromagnetic fluctuations, which physicists call noise. The more noise there is, the longer the detector must sit at each tuning step to listen for an axion signal.

Unfortunately, researchers can’t count on picking up the axion broadcast after a few dozen turns of the radio dial. An FM radio tunes from only 88 to 108 megahertz (one megahertz is one million hertz). The axion frequency, by contrast, may be anywhere between 300 hertz and 300 billion hertz. At the rate today’s detectors are going, finding the axion or proving that it doesn’t exist could take more than 10,000 years.

Squeezing the quantum noise

On the HAYSTAC team, we don’t have that kind of patience. So in 2012 we set out to speed up the axion search by doing everything possible to reduce noise. But by 2017 we found ourselves running up against a fundamental minimum noise limit because of a law of quantum physics known as the uncertainty principle.

The uncertainty principle states that it is impossible to know the exact values of certain physical quantities simultaneously – for instance, you can’t know both the position and the momentum of a particle at the same time. Recall that axion detectors search for the axion by measuring two quadratures – those specific kinds of electromagnetic field oscillations. The uncertainty principle prohibits precise knowledge of both quadratures by adding a minimum amount of noise to the quadrature oscillations.

In conventional axion detectors, the quantum noise from the uncertainty principle obscures both quadratures equally. This noise can’t be eliminated, but with the right tools it can be controlled. Our team worked out a way to shuffle around the quantum noise in the HAYSTAC detector, reducing its effect on one quadrature while increasing its effect on the other. This noise manipulation technique is called quantum squeezing.

In an effort led by graduate students Kelly Backes and Dan Palken, the HAYSTAC team took on the challenge of implementing squeezing in our detector, using superconducting circuit technology borrowed from quantum computing research. General-purpose quantum computers remain a long way off, but our new paper shows that this squeezing technology can immediately speed up the search for dark matter.

Bigger bandwidth, faster search

Our team succeeded in squeezing the noise in the HAYSTAC detector. But how did we use this to speed up the axion search?

Quantum squeezing doesn’t reduce the noise uniformly across the axion detector bandwidth. Instead, it has the largest effect at the edges. Imagine you tune your radio to 88.3 megahertz, but the station you want is actually at 88.1. With quantum squeezing, you would be able to hear your favorite song playing one station away.

In the world of radio broadcasting this would be a recipe for disaster, because different stations would interfere with one another. But with only one dark matter signal to look for, a wider bandwidth allows physicists to search faster by covering more frequencies at once. In our latest result we used squeezing to double the bandwidth of HAYSTAC, allowing us to search for axions twice as fast as we could before.

Quantum squeezing alone isn’t enough to scan through every possible axion frequency in a reasonable time. But doubling the scan rate is a big step in the right direction, and we believe further improvements to our quantum squeezing system may enable us to scan 10 times faster.

Nobody knows whether axions exist or whether they will resolve the mystery of dark matter; but thanks to this unexpected application of quantum technology, we’re one step closer to answering these questions.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Quantum squeezing alone isn’t enough to scan through every possible axion frequency in a reasonable time

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From Biden’s giant Bible to Christian flags waved by rioters, ‘religion’ means different things to different people and different eras

Anonymous — Thu, 21 Jan 2021 15:01:58 +0000

From Biden’s giant Bible to Christian flags waved by rioters, ‘religion’ means different things to different people and different eras Anonymous (not verified) Thu, 01/21/2021 - 08:01

Samuel L. Boyd

A similar complexity appears in the history of early Christianity in how religion functioned, both in terms of rituals and in the use of the Latin term it derives from

The Bible featured prominently in the inauguration. In fact, three were used in the swearing-in ceremonies – Kamala Harris used both Thurgood Marshall’s and one belonging to a friend; Joseph Biden used a 128-year-old family Bible.

�鶹ӰԺ two weeks earlier, on Jan. 6, rioters who stormed the U.S. Capitol also held Bibles as a nod to the apparent religious motivations for their actions. The mob took with them flags saturated with Christian nationalist ideology, such as banners with “Jesus Saves” written on them accompanied by chants that “Christ is king, Trump is president.”

At the top of the page: President-elect Joe Biden takes the oath of office during the 59th presidential inauguration on Jan. 20, 2021, at the US Capitol in Washington, DC. Pool photo by Andrew Harnik. Above: Jill Biden holds the Bible as Joe Biden is sworn in as the 46th president of the United States on Jan. 20, 2021. Saul Loeb/Pool Photo via AP

These and other religious symbols, used both in the service of the presidential transfer of power and also violent protests, demonstrate how deeply religion can motivate people in society and influence their actions politically.

Yet the way people think about religion these days, often as a set of beliefs, has evolved across time and cultures.

Religion in ancient Near East

As a scholar of the Bible and the ancient Near East, I study the role of religion in history and how this term originated and came to be understood over the centuries.

For most cultures in the ancient world, such as Egypt, Assyria and Babylon, until the second century B.C., there was no word for “religion” as a singular, abstract concept.

While these cultures had rituals and rites for worshiping gods and goddesses, there was not a singular word in these languages that refers to “religion” in the modern sense. For example, the Assyrians had a unique blend of religious devotion to their chief god Assur and a belief in a divine mandate to spread their empire, but they did not have one word to cover all such practices and beliefs.

The same is true for the Old Testament, written in Hebrew and Aramaic from approximately the ninth century B.C. to the second century B.C. There is no word that can really be translated as “religion” in the modern sense in the Old Testament, even if there were religious concepts, such as prayers and acts of piety toward the god of Israel.

The evidence from the ancient Near East and the Old Testament points to a complex set of practices that defy a singular notion of religion, such as a creed of faith or spirituality in distinction from other realms of society such as politics or economics.

Early Christianity

A similar complexity appears in the history of early Christianity in how religion functioned, both in terms of rituals and in the use of the Latin term it derives from.

The word “religion” in English originates from the Latin “religio.” One of its earliest appearances is in works such as the plays of second-century B.C. writer Plautus.

According to the classicist Niall Slater, the word defies “a theologically rigorous definition” in Plautus. It means something like “awe” in one passage, as well as reserve, in the often ironic sense of characters who find themselves in situations in which they display restraints from certain impulses. For example, in one scene in Plautus’ “Asinaria,” a woman is bound by a contract from following other male lovers, including gods, a restraint called “religiosa.”

In the classical age, religion could possibly imply “scruples,” as evident in the writings of Plautus and certainly a few decades later in the writings of playwright Publius Terentius Afer.

By the first century B.C., the word began to be associated with devotion to the divine realm. As seen in the writings of the orator and politician Cicero, one conception of the Latin religio that became frequent in Roman texts was the specific rituals and rites that were a part of worship of the gods and goddesses.

According to the classicist Clifford Ando and scholar of religion Brent Nongbri, for Cicero each ritual could be a religio, and, at the same time, when Romans performed all such rituals they could together be referred to as a “single, Roman, religio.”

However, Roman thinkers did not use this term for Christianity in its earliest phases. In the second century A.D., Roman writers such as Pliny, Tacitus and Suetonius labeled Christianity not a religio but rather a superstitio, or a “superstition,” a term usually applied to non-Roman, foreign practices.

Eventually Galen, a physician and philosopher who died in A.D. 210 in Rome, would call Christianity a “philosophical school,” elevating the status of the movement.

Early Christians who wrote in Latin, beginning with Tertullian in the second century A.D., often used the word religio to refer to their own rituals and rites, though other uses appeared as well, which were inherited from the variety of definitions employed by earlier Latin writers.

The ancient Latin translations of the New Testament, which was originally written in Greek, use religio when rendering passages such as James 1:26-27, which described true religion as care for orphans and widows and keeping oneself unstained from worldly pollution, or sin.

Kamala Harris is sworn in as vice president as her husband Doug Emhoff holds the Bible during the 59th presidential inauguration at the U.S. Capitol in Washington, D.C. AP Photo/Andrew Harnik

Modern-day interpretation

So how did the modern interpretation of religion come about?

If, according to 19th-century German philosopher Ludwig Feuerbach, humans are prone to imagining God in their own image, then according to the scholar of religion Brent Nongbri people are often tempted to do the same with our understanding of the word “religion.”

As Nongbri observes, people need to be aware that when they encounter the word “religion” in English translations of ancient sources, it is not the same as spirituality or belief in the sense of an abstract set of convictions.

Often religion is thought of as referring to some inner disposition or abstract belief, such as privately held convictions about salvation separate from politics. The 17th-century thinker John Locke argued this point in his book, “A Letter Concerning Toleration.”

Yet, as Nongbri argues, the concept of religion as an activity distinct from others, such as “politics, economics, and science,” is a recent and modern contrast, alien to ancient societies. In ancient societies, religion was part of every facet of life because gods and goddesses were involved in every facet of life.

Indeed, the inner, spiritual and privatized nature of what many think of as religion is more a reflection of modern Protestant Christian developments and has little to do with the origins of the term.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

A similar complexity appears in the history of early Christianity in how religion functioned, both in terms of rituals and in the use of the Latin term it derives from.

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Engineers of the mysterious pit traps

Anonymous — Wed, 16 Sep 2020 16:40:32 +0000

Engineers of the mysterious pit traps Anonymous (not verified) Wed, 09/16/2020 - 10:40

They are secretive and cryptic, but you can see them if you know what to look for

What causes those conical divots in the soft, dry soil beneath large conifers in the mountains and at the bases of cliffs on the Colorado Plateau? They presented a mystery when I first noticed them, for it was evident that something must be both constructing and maintaining them. Otherwise, breezes and gusts would soon fill them with sand, dust and forest litter. Yet they seem to be empty and unattended.

Top of page: Adult Antlion Above: Antlion larvae dig pit traps in the duff beneath large ponderosa pines. Photos by Jeff Mitton.

Antlion larvae are the denizens of the pits. They are secretive and cryptic, but you can see them if you know what to look for. They are often just beneath the sand at the base of the trap, but occasionally they wait with their heads and curved mandibles exposed. But you must look closely, for a larva is only about a half inch in length and the head and mandibles are about a third of that length.

The larva is grotesque, with large, curved mandibles bearing sharp spines, a flattened head on a flexible neck, six legs and a hairy body that tapers to the rear. It rarely walks on the surface, but it effectively swims backward through soft soil, rowing with its legs and sculling with its tail. The hairs on all parts of its body point forward, so they fold down neatly against the body when the legs push it backward, but become erect and embedded, effectively anchoring the larva when the legs return for another push, or when an animal tries to pull it out of the soil.

When a larva is searching for an appropriate spot to dig a pit trap, it wanders about, moving just beneath the surface. It needs a spot that is shaded in the afternoon, because afternoon soil surface temperatures can be lethal. It also needs to be protected from the rain because the walls of the pit must be dry to work effectively — ants can easily walk out of a trap on firm, moist soil. The larva's path during this search wanders, wiggles and circles, and the path, evident as a shallow trench, looks like something has doodled in the sand. Consequently, some people call them doodlebugs.

When a larva finds a suitable spot, it begins to move in a circle with a diameter of about one inch, using its head as a scoop to toss sand or dust outside the circle. It continues, in ever tightening circles, moving and tossing, forming a conical pit with steep walls. Depending on the size of the soil particles, the sides of the pit will form a "natural slope" which is the maximum angle at which the soil is stable. This is analogous to the perfect cone that forms when sand falls through an hourglass--the sand accumulates and slides until it finds the natural slope. When the pit walls have attained the natural slope, the larva buries itself at the bottom of the pit and waits.

Antlion larvae dig pit traps in the duff beneath large ponderosa pines. Photo by Jeff Mitton.

Sooner or later, a foraging ant (or beetle, spider, or pill bug) will wander into the pit and its weight will cause the sand beneath its feet to slide. Naturally, it would attempt to climb out, causing the sand to slide even more. The larva reacts by flicking sand up onto the struggling animal, slowing the struggler and increasing the amount of sliding sand. If the ant slides to the bottom, the antlion's jaws close, piercing the ant and injecting a venom through its hollow jaws. The venom contains bacterial compounds that paralyze, digest and dissolve the prey's tissues, which are then sucked through the hollow jaws. When the animal has been drained, the larva flicks the carcass up and out of the pit. Trapping and consumption of an ant takes about an hour.

Antlion larvae live two to three years, depending on species and environment."

Antlion larvae live two to three years, depending on species and environment. Adults, which have four wings and wingspans of three to four inches, eat nectar and pollen and live just a few weeks.

Antlion traps can be found in the bare dry soil beneath large ponderosa pines and Douglas-firs in the foothills around �鶹ӰԺ — dozens may be found beneath a single tree. In canyon country, look at the base of walls and cliffs. When you have located pit traps, you can search for the antlions with a magnifying glass, looking for the characteristic shape of the curved jaws. An antlion larva can be provoked to flick sand by touching the side of the pit with a fine piece of straw, causing sand to slide. To get a better look, thrust a trowel beside and beneath a pit and place the soil into a sieve or aquarium net, then search through the soil for the larva. It will be cryptic, for the hairs hold much sand. Finally, return the larva to soft soil and watch it bury itself.

This article is part of Jeff Mitton's ongoing blog, Natural Selections.

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Baptism by Zoom, now taking off, has deep historical roots

Anonymous — Tue, 24 Mar 2020 15:44:42 +0000

Baptism by Zoom, now taking off, has deep historical roots Anonymous (not verified) Tue, 03/24/2020 - 09:44

Samuel L. Boyd

Faith leaders are coming up with new ways to reach their communities

The coronavirus pandemic is forcing entire countries to rethink deeply-held social norms. Faith leaders are coming up with new ways to reach their communities, with many turning to online platforms to perform rituals.

Among the services being offered via new technology are some of the most fundamental customs, or rituals, such as baptism. This ritual in Christianity normally involves either sprinkling or immersion in water and signals a special connection between the baptized individual, God and the religious community.

Religious rituals have always evolved in the face of changing circumstances."

Some churches are now offering Zoom sessions in which a priest or pastor virtually places water on an individual.

This might seem surprising to those who believe that religious rituals are unchanging or frozen reflections of past practice.

As an historian of the Bible, I know that religious rituals have always evolved in the face of changing circumstances. A particularly important example of this change occurred when the temple in Jerusalem was destroyed, twice.

Following the destruction, the way that Jewish communities worshiped God changed forever.

Temple worship

The temple in Jerusalem occupies an important place in both Jewish and Christian thought. David, the King of Israel who ruled from around 1010 to 970 B.C., is said to have first envisioned the temple. It was, however, built by his son Solomon.

The temple played a central role in ancient Israelite worship. According to the Bible, the temple in Jerusalem was where God lived. The belief was that as long as God remained in Jerusalem, the city would be indestructible.

In 701 B.C., a king named Sennacherib tried to invade Jerusalem but was unsuccessful. The military campaign devastated the surrounding villages, but Jerusalem survived. According to some biblical texts, God had chosen the temple as a special place to dwell.

Sacrifices were performed in the temple to ensure that God stayed forever in Jerusalem. The belief was that the sacrifices provided food for God.

The blood from the sacrifices was also intended as a purge. It was believed that sinful actions of Israelites could travel through the air, generating a stain, called a “miasma.”

This stain was believed to stick to various parts of the temple. According to the Book of Leviticus, in the Old Testament, the more important the person in Israelite society committing the sin, the closer the stain would land to the place where God was believed to have lived, called the “Holy of Holies.”

The blood of sacrifices was applied to these places, making God’s dwelling clean and tidy.

As such, these sacrifices were designed to keep God happy and they were essential to maintaining order in the divine dwelling.

Religious reordering

Except that the biblical texts claim that God did not stay in the temple forever. According to the Book of Ezekiel in the Bible, God became unhappy with the state of affairs in Jerusalem and abandoned the temple.

Model of Jerusalem in the late Second Temple period. Dan Lundberg/Flickr, CC BY-SA

Following the divine abandonment Jerusalem was no longer indestructible. In 586 B.C., Nebuchadnezzar, a Babylonian king, conquered Jerusalem and destroyed the temple.

The temple was rebuilt around 515 B.C. But this “Second Temple” too was destroyed, this time by the Romans in 70 A.D.

This destruction left Jewish leaders with profound questions. Without a temple, they asked, how could people access God and offer sacrifices.

Another vital question before them was: How were these Jewish communities to relate to God, particularly in view of the commands of sacrifice in the Bible, when the temple was gone?

Ritual innovation

Religious texts were believed to hold answers for why these disasters occurred.

According to the scholar James Kugel, Jewish prophets and sages explained that these events were “God’s punishment” for the failure to “obey the divine laws.”

As a result, those who survived were “resolved to learn the lesson of history” by studying ancient texts and performing the laws as God intended. In this way, it was believed, they would find “favor with God” and “head off another disaster,” according to Kugel.

Other scholars, such as Mira Balberg and Simeon Chavel, have argued that the same biblical texts were also thought to contain the key for constructing new religious ideas. In fact, these texts gave license for ritual innovation in light of changing historical circumstances.

Such innovations were often, though not always, grounded in sacred texts and traditions. That way they had a continuity with the past.

Adapting to change

[video:https://youtu.be/FyCL2UYYHTs width:560 height:315 align:right]

Reciting the Amidah.

It was through this process that prayer in the Jewish tradition came to be seen as a form of sacrifice.

Both the act of sacrifice and prayer connected the divine and human realms. Some passages in the Bible made the connection explicit.

For example, Psalm 141:2 that says, “Take my prayer as an offering of incense, my upraised hands as an evening sacrifice,” drew similarities between prayer and sacrifice. So did another book in the Bible – Hosea 14:3, which says, “Instead of bulls we will pay the offering of our lips.”

The verses even put prayer and sacrifice in parallel poetic lines as a way to almost equate the actions.

In fact, the prayer in Judaism known as the “Amidah” was conceived as a substitute for sacrifice very shortly after the destruction of the Second Temple.

The destruction of the temple created unimaginable crises in the religious sensibilities of ancient Jews, but also became a platform to reimagine how religious ritual worked.

The ability for modern religious communities to adapt and innovate rituals in light of circumstances, then, has deep and very productive roots.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Faith leaders are coming up with new ways to reach their communities, with many turning to online platforms to perform rituals.

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