IP属地:上海
4楼2015-01-28 18:05
4楼2015-01-28 18:05收起回复
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【Scientists slow down the speed of light travelling through air】
Scientists have long known that the speed of light can be slowed slightly as it travels through materials such as water or glass.
However, it has generally been thought impossible for particles of light, known as photons, to be slowed as they travel through free space, unimpeded by interactions with any materials.In a new paper published in Science Express today (Friday 23 January), researchers from the University of Glasgow and Heriot-Watt University describe how they have managed to slow photons in free space for the first time. They have demonstrated that applying a mask to an optical beam to give photons a spatial structure can reduce their speed. Their experiment was configured like a race, with two photons released simultaneously across identical distances towards a defined finish line.The team compare a beam of light, containing many photons, to a team of cyclists who share the work by taking it in turns to cycle at the front. Although the group travels along the road as a unit, the speed of individual cyclists can vary as they swap position.
The group formation can make it difficult to define a single velocity for all cyclists, and the same applies to light. A single pulse of light contains many photons, and scientists know that light pulses are characterised by a number of different velocities.The researchers found that one photon reached the finish line as predicted, but the structured photon which had been reshaped by the mask arrived later, meaning it was travelling more slowly in free space. Over a distance of one metre, the team measured a slowing of up to 20 wavelengths, many times greater than the measurement precision.The work demonstrates that, after passing the light beam through a mask, photons move more slowly through space. Crucially, this is very different to the slowing effect of passing light through a medium such as glass or water, where the light is only slowed during the time it is passing through the material – it returns to the speed of light after it comes out the other side. The effect of passing the light through the mask is to limit the top speed at which the photons can travel.The work was carried out by a team from the University of Glasgow’s Optics Group, led by Professor Miles Padgett, working with theoretical physicists led by Stephen Barnett, and in partnership with Daniele Faccio from Heriot-Watt University.Daniel Giovannini, one of the lead authors of the paper, said: “The delay we’ve introduced to the structured beam is small, measured at several micrometres over a propagation distance of one metre, but it is significant. We’ve measured similar effects in two different types of beams known as Bessel beams and Gaussian beams.”Co-lead author Jacquiline Romero said: “We’ve achieved this slowing effect with some subtle but widely-known optical principles. This finding shows unambiguously that the propagation of light can be slowed below the commonly accepted figure of 299,792,458 metres per second, even when travelling in air or vacuum. “Although we measure the effect for a single photon, it applies to bright light beams too. The effect is biggest when the lenses used to create the beam are large and when the distance over which the light is focused is small, meaning the effect only applies at short range.”Professor Padgett added: “It might seem surprising that light can be made to travel more slowly like this, but the effect has a solid theoretical foundation and we’re confident that our observations are correct.“The results give us a new way to think about the properties of light and we’re keen to continue exploring the potential of this discovery in future applications. We expect that the effect will be applicable to any wave theory, so a similar slowing could well be created in sound waves, for example.”The team’s paper, titled ‘Spatially Structured Photons that Travel in Free Space Slower than the Speed of Light’, is published in Science Express, which provides electronic publication of selected papers in advance of print in the journalScience.
Scientists have long known that the speed of light can be slowed slightly as it travels through materials such as water or glass.
However, it has generally been thought impossible for particles of light, known as photons, to be slowed as they travel through free space, unimpeded by interactions with any materials.In a new paper published in Science Express today (Friday 23 January), researchers from the University of Glasgow and Heriot-Watt University describe how they have managed to slow photons in free space for the first time. They have demonstrated that applying a mask to an optical beam to give photons a spatial structure can reduce their speed. Their experiment was configured like a race, with two photons released simultaneously across identical distances towards a defined finish line.The team compare a beam of light, containing many photons, to a team of cyclists who share the work by taking it in turns to cycle at the front. Although the group travels along the road as a unit, the speed of individual cyclists can vary as they swap position.
The group formation can make it difficult to define a single velocity for all cyclists, and the same applies to light. A single pulse of light contains many photons, and scientists know that light pulses are characterised by a number of different velocities.The researchers found that one photon reached the finish line as predicted, but the structured photon which had been reshaped by the mask arrived later, meaning it was travelling more slowly in free space. Over a distance of one metre, the team measured a slowing of up to 20 wavelengths, many times greater than the measurement precision.The work demonstrates that, after passing the light beam through a mask, photons move more slowly through space. Crucially, this is very different to the slowing effect of passing light through a medium such as glass or water, where the light is only slowed during the time it is passing through the material – it returns to the speed of light after it comes out the other side. The effect of passing the light through the mask is to limit the top speed at which the photons can travel.The work was carried out by a team from the University of Glasgow’s Optics Group, led by Professor Miles Padgett, working with theoretical physicists led by Stephen Barnett, and in partnership with Daniele Faccio from Heriot-Watt University.Daniel Giovannini, one of the lead authors of the paper, said: “The delay we’ve introduced to the structured beam is small, measured at several micrometres over a propagation distance of one metre, but it is significant. We’ve measured similar effects in two different types of beams known as Bessel beams and Gaussian beams.”Co-lead author Jacquiline Romero said: “We’ve achieved this slowing effect with some subtle but widely-known optical principles. This finding shows unambiguously that the propagation of light can be slowed below the commonly accepted figure of 299,792,458 metres per second, even when travelling in air or vacuum. “Although we measure the effect for a single photon, it applies to bright light beams too. The effect is biggest when the lenses used to create the beam are large and when the distance over which the light is focused is small, meaning the effect only applies at short range.”Professor Padgett added: “It might seem surprising that light can be made to travel more slowly like this, but the effect has a solid theoretical foundation and we’re confident that our observations are correct.“The results give us a new way to think about the properties of light and we’re keen to continue exploring the potential of this discovery in future applications. We expect that the effect will be applicable to any wave theory, so a similar slowing could well be created in sound waves, for example.”The team’s paper, titled ‘Spatially Structured Photons that Travel in Free Space Slower than the Speed of Light’, is published in Science Express, which provides electronic publication of selected papers in advance of print in the journalScience.
有道机翻╮(╯▽╰)╭
【科学家减慢光速穿越空气】
科学家早就知道光速可以略有放缓,因为它穿过水或玻璃等材料。
然而,它通常被认为不可能光粒子,称为光子,将放缓,因为他们通过自由空间旅行,畅通的互动与任何材料。在一篇发表在《科学快讯》今天(星期五)1月23日,格拉斯哥大学、赫瑞瓦特大学研究人员描述他们如何设法减缓光子首次在自由空间。他们已经表明,应用一个面具的光束给光子空间结构可以减少他们的速度。他们的实验配置像一场比赛,有两个光子同时发布在相同的距离定义终点线。包含许多的团队比较一束光,光子,一群骑自行车的人谁分享工作轮流循环在前面。虽然组织沿道路作为一个单元,个人骑自行车的速度可能会有所不同,因为他们交换位置。
群体形成可以很难定义一个速度骑自行车的人,也一样。一个光脉冲包含了许多光子,科学家们知道,光脉冲的特点是许多不同的速度。研究人员发现,一个光子到达终点线正如预测的那样,但结构化光子被面具来重塑后,这意味着它在自由空间旅行更慢。在一米的距离,团队测量20波长的放缓,许多倍的测量精度。这项工作表明,在通过光束通过一个面具,光子通过空间移动更慢。至关重要的是,这是非常不同的减速效果传递光通过介质如玻璃或水,光只是放缓时它是通过材料——它返回到光速后出来的另一边。光线穿过面具的作用是限制最高时速的光子可以旅行。工作是由一个团队来自格拉斯哥大学的光学集团由英里帕吉特教授领导,与领导的理论物理学家史蒂芬•巴奈特与赫瑞瓦特大学的丹尼尔·西奥和伙伴关系。丹尼尔Giovannini论文的作者之一,表示:“延迟我们已经介绍了结构化梁小,测量在几个微米的传播距离1米,但它是重要的。我们测量了类似的影响在两种不同类型的光束被称为贝塞尔光束和高斯光束。”该研究Jacquiline罗梅罗表示:“我们已经达到了这个减速效果与一些微妙而著名的光学原理。这一发现无疑表明,光的传播可以减缓低于299792458米每秒的广泛接受的图,即使在空气或真空旅行。“虽然我们测量单个光子的作用,它也适用于明亮的光束。镜头时的最大影响是用于创建梁大当光线聚焦的距离很小,意义只应用在比较短的距离里面造成的影响。”帕吉特教授补充说:“它可能看起来奇怪,光可以使旅行更慢,但是效果有一个坚实的理论基础,我们相信,我们的观察是正确的。“结果给我们一种新的方式思考光的属性,我们希望未来继续探索这一发现的潜在应用。我们预计的效果将会适用于任何波浪理论,所以类似的放缓可能创建了声波,例如。”团队的论文,题为《空间结构的光子,在自由空间旅行比光速慢”,发表在《科学快讯》,它提供了电子出版物的事先选定的论文在《打印。
【科学家减慢光速穿越空气】
科学家早就知道光速可以略有放缓,因为它穿过水或玻璃等材料。
然而,它通常被认为不可能光粒子,称为光子,将放缓,因为他们通过自由空间旅行,畅通的互动与任何材料。在一篇发表在《科学快讯》今天(星期五)1月23日,格拉斯哥大学、赫瑞瓦特大学研究人员描述他们如何设法减缓光子首次在自由空间。他们已经表明,应用一个面具的光束给光子空间结构可以减少他们的速度。他们的实验配置像一场比赛,有两个光子同时发布在相同的距离定义终点线。包含许多的团队比较一束光,光子,一群骑自行车的人谁分享工作轮流循环在前面。虽然组织沿道路作为一个单元,个人骑自行车的速度可能会有所不同,因为他们交换位置。
群体形成可以很难定义一个速度骑自行车的人,也一样。一个光脉冲包含了许多光子,科学家们知道,光脉冲的特点是许多不同的速度。研究人员发现,一个光子到达终点线正如预测的那样,但结构化光子被面具来重塑后,这意味着它在自由空间旅行更慢。在一米的距离,团队测量20波长的放缓,许多倍的测量精度。这项工作表明,在通过光束通过一个面具,光子通过空间移动更慢。至关重要的是,这是非常不同的减速效果传递光通过介质如玻璃或水,光只是放缓时它是通过材料——它返回到光速后出来的另一边。光线穿过面具的作用是限制最高时速的光子可以旅行。工作是由一个团队来自格拉斯哥大学的光学集团由英里帕吉特教授领导,与领导的理论物理学家史蒂芬•巴奈特与赫瑞瓦特大学的丹尼尔·西奥和伙伴关系。丹尼尔Giovannini论文的作者之一,表示:“延迟我们已经介绍了结构化梁小,测量在几个微米的传播距离1米,但它是重要的。我们测量了类似的影响在两种不同类型的光束被称为贝塞尔光束和高斯光束。”该研究Jacquiline罗梅罗表示:“我们已经达到了这个减速效果与一些微妙而著名的光学原理。这一发现无疑表明,光的传播可以减缓低于299792458米每秒的广泛接受的图,即使在空气或真空旅行。“虽然我们测量单个光子的作用,它也适用于明亮的光束。镜头时的最大影响是用于创建梁大当光线聚焦的距离很小,意义只应用在比较短的距离里面造成的影响。”帕吉特教授补充说:“它可能看起来奇怪,光可以使旅行更慢,但是效果有一个坚实的理论基础,我们相信,我们的观察是正确的。“结果给我们一种新的方式思考光的属性,我们希望未来继续探索这一发现的潜在应用。我们预计的效果将会适用于任何波浪理论,所以类似的放缓可能创建了声波,例如。”团队的论文,题为《空间结构的光子,在自由空间旅行比光速慢”,发表在《科学快讯》,它提供了电子出版物的事先选定的论文在《打印。
IP属地:江西15楼2015-01-28 20:35
15楼2015-01-28 20:35收起回复
终于翻译完了Orz好累，容我看一集空境冷静一下= =
科学家们很早以前就知道：光在介质（例如水或者玻璃）中传播时，速度会降低。
而通常来说，对于光的微粒，即光子，被认为是不可能降低其在自由空间（free space，在经典物理里，自由空间是电磁理论的一种概念，指的是一种理论的完美真空，不含有任何物质的真空。有时候，自由空间又称为自由空间真空，或经典真空。自由空间可以恰当地被视为一种参考介质。摘自wiki）中的速度的。
在一篇发表于1月23日（星期五）的《ScienceExpress》（貌似是美国科学周刊《ScienceMag》的一个栏目）上的论文中，和来自格拉斯哥大学和赫瑞瓦特大学的研究人员介绍了他们如何首次做到降低光子在自由空间中的速度。他们演示了用一个遮挡物（mask）去作用一束光，用一个空间结构降低了光的速度。
他们的实验设置的像一场竞速，两个光子同时被释放，他们经过等长的路径，到达一个清晰的终点。
用一支队伍比喻包含了很多的光子的一束光，队伍里的骑手分工合作，轮流骑车向前。尽管是整个小组以整体通过赛道，但是每一个骑手个体的速度也是随着他们整体交换位置而变化。
比赛小组的数据信息使明确单独骑手的速率变得困难，光束同理。一束单独光脉冲包含了很多光子。科学家们知道，一束光脉冲包含了很多不同速度的光子（are characterised by a number of different velocities.）。
研究人员发现，对照组光子按预期到达了终点线，但是被特殊结构作用的光子却较晚到达，这说明它在自由空间中的速度降低了。经过1米的距离，研究团队测量出了超过20个波长的差值，有很多次实验值甚至更大。
这个试验表明，当光束穿过遮挡物（mask）时，光子空间运动速度变慢了。至关重要的是，这和穿过介质（诸如水和玻璃）时光速变慢的原理十分不同。不同于前者离开介质后光速就恢复了，这个试验中，遮挡物（mask）限制了光束前进的最高速度。
这个实验由一个格拉斯哥大学的光学研究团队组织，领队是Miles Padgett教授。这个团队和Stephen Barnett领队的理论物理学家们一起工作，同时和来自赫瑞瓦特大学的Daniele Faccio合作。
论文的主要作者之一Daniel Giovannini说：“我们演示的光速降幅非常小，每传播1米只有几微米的路径延后，但是这是有重大意义的。我们已经用其他两种光束——Bessel光和Gaussian光做出了类似的效果。”
联席主要作者（co-lead author，这个不知道怎么翻译准确）Jacquiline Romero说：“我们已经成功用几条微妙但是广为人知的光学定律来描述这个效应了。这个研究结果明确表明：光的传播能被减缓，低于被普遍接受的数值299,792,458米每秒，甚至在空气和真空中都能做到。”
“尽管我们我们测量的是单个光子，但是依然可以应用于一束亮光。当用来制造光束的透镜很大而且光束聚集的距离很短时，这个效应会达到最大，这意味着这个效应只能在小范围内应用。”
Padgett教授补充道：“能使光速像这样降低或许会使你感到惊讶，但是这个效应拥有坚实的理论基础，我们相信我们的观测是正确的。”
“这个结果给了我们一个新的思考光特性的途径，我们希望继续研究这个发现在未来应用中的潜能。我们希望这个效应能够适用于所有的波动理论，那么类似的效应就能被实现，比如降低音速。”
这个团队的论文以“空间结构作用光子在自由空间中的传播速度低于光速”为题，发表于《Science Express》,一个刊登相关论文的电子科学出版物，所刊论文超过《科学》杂志。（which provides electronic publication of selected papers in advance ofprint in the journal Science应该是比《科学》期刊更牛的意思吧= =）
科学家们很早以前就知道：光在介质（例如水或者玻璃）中传播时，速度会降低。
而通常来说，对于光的微粒，即光子，被认为是不可能降低其在自由空间（free space，在经典物理里，自由空间是电磁理论的一种概念，指的是一种理论的完美真空，不含有任何物质的真空。有时候，自由空间又称为自由空间真空，或经典真空。自由空间可以恰当地被视为一种参考介质。摘自wiki）中的速度的。
在一篇发表于1月23日（星期五）的《ScienceExpress》（貌似是美国科学周刊《ScienceMag》的一个栏目）上的论文中，和来自格拉斯哥大学和赫瑞瓦特大学的研究人员介绍了他们如何首次做到降低光子在自由空间中的速度。他们演示了用一个遮挡物（mask）去作用一束光，用一个空间结构降低了光的速度。
他们的实验设置的像一场竞速，两个光子同时被释放，他们经过等长的路径，到达一个清晰的终点。
用一支队伍比喻包含了很多的光子的一束光，队伍里的骑手分工合作，轮流骑车向前。尽管是整个小组以整体通过赛道，但是每一个骑手个体的速度也是随着他们整体交换位置而变化。
比赛小组的数据信息使明确单独骑手的速率变得困难，光束同理。一束单独光脉冲包含了很多光子。科学家们知道，一束光脉冲包含了很多不同速度的光子（are characterised by a number of different velocities.）。
研究人员发现，对照组光子按预期到达了终点线，但是被特殊结构作用的光子却较晚到达，这说明它在自由空间中的速度降低了。经过1米的距离，研究团队测量出了超过20个波长的差值，有很多次实验值甚至更大。
这个试验表明，当光束穿过遮挡物（mask）时，光子空间运动速度变慢了。至关重要的是，这和穿过介质（诸如水和玻璃）时光速变慢的原理十分不同。不同于前者离开介质后光速就恢复了，这个试验中，遮挡物（mask）限制了光束前进的最高速度。
这个实验由一个格拉斯哥大学的光学研究团队组织，领队是Miles Padgett教授。这个团队和Stephen Barnett领队的理论物理学家们一起工作，同时和来自赫瑞瓦特大学的Daniele Faccio合作。
论文的主要作者之一Daniel Giovannini说：“我们演示的光速降幅非常小，每传播1米只有几微米的路径延后，但是这是有重大意义的。我们已经用其他两种光束——Bessel光和Gaussian光做出了类似的效果。”
联席主要作者（co-lead author，这个不知道怎么翻译准确）Jacquiline Romero说：“我们已经成功用几条微妙但是广为人知的光学定律来描述这个效应了。这个研究结果明确表明：光的传播能被减缓，低于被普遍接受的数值299,792,458米每秒，甚至在空气和真空中都能做到。”
“尽管我们我们测量的是单个光子，但是依然可以应用于一束亮光。当用来制造光束的透镜很大而且光束聚集的距离很短时，这个效应会达到最大，这意味着这个效应只能在小范围内应用。”
Padgett教授补充道：“能使光速像这样降低或许会使你感到惊讶，但是这个效应拥有坚实的理论基础，我们相信我们的观测是正确的。”
“这个结果给了我们一个新的思考光特性的途径，我们希望继续研究这个发现在未来应用中的潜能。我们希望这个效应能够适用于所有的波动理论，那么类似的效应就能被实现，比如降低音速。”
这个团队的论文以“空间结构作用光子在自由空间中的传播速度低于光速”为题，发表于《Science Express》,一个刊登相关论文的电子科学出版物，所刊论文超过《科学》杂志。（which provides electronic publication of selected papers in advance ofprint in the journal Science应该是比《科学》期刊更牛的意思吧= =）
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